(Adds link to map showing population of border area)
* Funerals held daily for Hezbollah soldiers killed in Syria
* Syrian opposition members ask Hezbollah to withdraw men
* Sunni Syria rebels fire missiles into Shi'ite Lebanon town
By Oliver Holmes
BAALBEK, Lebanon, April 26 (Reuters) - Along north Lebanon's highways, the portraits of Hezbollah militants who have died in skirmishes with Israel are fading. But there are glistening photos of those killed in Hezbollah's new fight.
These men died in Syria, battling alongside the army of Hezbollah's close ally President Bashar al-Assad against rebel units in a conflict which has killed more than 70,000 people and risks reigniting Lebanon's 15-year sectarian civil war.
The Shi'ite Muslim group, designated a terrorist organisation by the United States, is the most effective military body in Lebanon and its growing involvement in Syria's quagmire has angered Lebanese Sunni rebel sympathisers.
The Hezbollah stronghold of Baalbek, famed for its colossal Roman ruins, now feels like a garrison town. Hezbollah men in military fatigues and police outfits are everywhere. As are Jeeps and Chevrolets with blacked-out windows - the group's vehicles of choice.
On Wednesday afternoon, machine gun fire rang out through Baalbek's narrow streets, signalling the arrival of another dead Hezbollah fighter from Syria, 12 km (7 miles) to the east.
Around 30 of his comrades quickly aligned in the street and straightened their green berets, readying themselves to carry the corpse on their shoulders.
"We have one or two of these funerals every day in Baalbek," said a young electronics shopkeeper, who asked to remain anonymous due to the sensitivity of the issue.
A Hezbollah policeman in a polyester blue shirt told Reuters not to film the public funeral. "There are five or six Hezbollah martyrs every day from northern Lebanon," he said quietly, ushering the car away.
AN OPEN SECRET
Lebanon endured a military presence by its historically dominant neighbour for 29 years until 2005 and has tried to maintain a policy of "dissociation" from Syria's once-peaceful uprising against four decades of family rule that turned violent after Assad's men killed and arrested thousands.
But insulating Lebanon's four million people from Syria proved impossible; refugees flooded in, Sunni villagers along the border began giving shelter, food and medical care to Syrian rebels and rebel supporters in Lebanon sent guns and fighters across the border to fight Assad's troops.
With no command structure, how many is hard to establish, but 12 Lebanese gunmen were killed by the Syrian army near Homs in November and residents in the Lebanese coastal town of Tripoli, where Sunnis sporadically clash with Alawites, say some local Sunnis fight in Syria, too.
Assad has told Lebanon, where power is distributed between Sunni Muslims, Maronite Christians and Shi'ite Muslims, it must help him fight what he calls "foreign-backed terrorist groups".
His men have regularly fired mortars into Lebanon and occasionally entered in pursuit of fleeing Syrian rebels.
Hezbollah, which was formed as a resistance group to the Israeli occupation during Lebanon's own civil war between 1975 and 1990, has been called in to help.
It maintains that it is keeping its weapons and huge missile caches to defend the country, but fighting a foreign war has stretched the definition of the group's mandate, angering those Lebanese who want to distance the country from Syria.
Officially, Hezbollah denies fighting in Syria. Asked about the latest escalation in the border area, Ibrahim Mussawi, Hezbollah's media relations officer, said: "For two years it has been our official policy not to comment."
But the secret is an open one. Michael Young, an opinion writer for the Beirut-based Daily Star, said in a column on Thursday that the pressure is likely coming from Shi'ite Iran, Hezbollah's main financier and supporter of Assad, who is himself an Alawite, an offshoot of Shi'ism.
"Hezbollah's becoming cannon fodder for the Syrian regime, at Iran's request, is not something the party must relish," he wrote. "There is a price to pay for Hezbollah's pushing the boundaries of Lebanon's sectarian system to its limits. And this price may be the party's gradual destruction, or worse, a Lebanese sectarian civil war."
Late on Wednesday, prominent Syrian opposition figure Moaz Alkhatib issued a direct appeal to Hezbollah leader Sayyed Hassan Nasrallah to withdraw fighters from Syria to prevent sectarian war engulfing the Middle East.
"The blood of your sons in Lebanon should not be spilled fighting our oppressed sons in Syria," Alkhatib said in a video message, following days of heavy fighting in Syria's Homs border province where rebels say Hezbollah is most active.
"Hezbollah's intervention in Syria has complicated matters greatly," he said.
Alkhatib, a Sunni former preacher in Damascus, said Sunni and Shi'ite Muslims had to overcome "a thousand years of strife" between their communities, or risk an explosion of sectarian conflict reaching from Syria and Lebanon to Turkey and Iran.
But already there have been calls to arms by influential Sunni Muslim preachers in Lebanon against Hezbollah, the "Party of God", risking a return to Lebanese bloodshed.
One of the most outspoken, Ahmad al-Assir, urged his supporters to fight Hezbollah inside Syria to help rebel groups, many of whom are hardline Islamist.
And on Saturday, Syria's al Qaeda-linked al-Nusra front broadcast a statement on the opposition Orient Television, saying rebel brigades would "move the battle into Lebanon" if the Hezbollah-backed offensive in Homs continued.
The statement said rebels would use tanks and missiles to hit Baalbek and move fighters into Lebanese territory to attack Hezbollah there. <^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Map of Lebanese border towns http://link.reuters.com/sut67t <^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
SYRIAN REBEL HATRED
Over the past two weeks, eight Grad rockets have landed in Shi'ite Hermel, a sprawling agricultural town of around 100,000 next to the Orontes river on Lebanon's border with Syria and about 45 km (28 miles) north of Baalbek.
One empty building was hit along Hermel's main thoroughfare, leaving a metre-wide hole. Another hit a house next to an orphanage further into the town and shrapnel pock-marked a nearby house. None have caused injuries, yet.
The mayor of Hermel, Hajj Saqr, said the missiles were fired by Syrian rebels, or as he calls them: "terrorists".
"If (the rebels) want change, then why do they fire into Lebanon?" he asked, saying Hermel has taken in 4,000 Syrian refugee families and helped the wounded.
"If the terrorists continue to attack and enter Lebanon, then we will protect ourselves," he said.
Saqr denied that men from his pro-Hezbollah town are making the 10 km (six mile) trip north to fight in Syria.
He said only that Lebanese citizens living just within Syria have set up their own civilian militia to protect themselves. Hezbollah also says its members in Lebanese-populated villages in Syria are "defending themselves."
But further up the road to Syria, lined with pictures of Assad and Iranian President Mahmoud Ahmadinejad, there is an evident military buildup. Hezbollah fighters are everywhere, some carrying big bags and walking north.
The group's private ambulance service runs back and forth across the Orontes. And as frogs croak by the river, a Syrian air force jet briefly enters Lebanese airspace before banking sharply and releasing two bombs on a town over the border. (Additional reporting by Dominic Evans; editing by Philippa Fletcher)