(Adds capture of Ras al-Ain, rockets in Qaa, details)
BEIRUT, March 19 (Reuters) - The Lebanese army reopened a road between two towns near the Syrian frontier on Wednesday to try to calm sectarian rivalry that has been aggravated by a Syrian government campaign to tighten its grip on the border region.
Shi'ite Muslims from the Lebanese Bekaa Valley town of al-Labwa had erected sandbag barriers at the weekend to cut off the road to Arsal, a Sunni town about 5 km (3 miles) east where they believed hundreds of Syrian rebels had taken refuge.
Tensions have been especially high in and around Arsal after Syrian forces and the Lebanese Shi'ite militant group Hezbollah recaptured the Syrian border town of Yabroud from rebels on Sunday, sending a stream of refugees and fighters across the border.
Lebanon's border area has been steadily sucked into Syria's three-year-old conflict as President Bashar al-Assad's forces attack nearby rebel bases and suspected Syrian rebels fire rockets at Shi'ite towns to punish Hezbollah for sending fighters to support Assad.
Also on Wednesday, Syrian government forces backed by Hezbollah fighters seized Ras al-Ain, a village southwest of Yabroud, and rockets suspected to have come from Syrian territory fell near the Lebanese border town of Qaa, 20 km (12 miles) northwest of al-Labwa.
A security source told Reuters the rockets caused no damage or casualties.
The anti-Assad Syrian Observatory for Human Rights monitoring group said the groups defending Ras al-Ain included the Nusra Front, al Qaeda's affiliate in Syria, and the Islamic State of Iraq and the Levant (ISIL), an al Qaeda splinter group. It did not provide casualty figures.
More than 140,000 people have been killed in the conflict, which has become increasingly sectarian as rival regional powers have backed either President Bashar al-Assad, a member of the Shi'ite offshoot Alawite sect, or the overwhelmingly Sunni rebels who oppose him.
SOUNDS OF BOMBARDMENT
Syrian state television broadcast what it said was live footage from inside Ras al-Ain where it interviewed an army officer about the defeated rebels.
"They cannot stand before the Syrian Arab Army. Wherever you find the Syrian Arab Army, there is safety, there is victory," he said.
State TV showed women and children ululating and waving Syrian flags in celebration at the army's arrival. "With our blood, with our souls, we sacrifice for you Bashar!" they chanted, as soldiers in fatigues stood nearby.
The mayor of al-Labwa, Ramez Amhaz, told Reuters the road to Arsal was reopened at around 6 a.m. (0400 GMT). "Traffic is back to normal," he said.
A Reuters witness in Arsal said people had welcomed the army's arrival, slaughtering sheep in the street in celebration. He said the opening resolved a shortage of flour caused by the roadblock.
The witness said he saw no sign of Syrian rebel fighters in Arsal but could hear the sound of bombardment coming from Syria. The blockade of Arsal had followed days of rocket attacks on al-Labwa which residents blamed on Syrian Sunni rebels.
Sunni demonstrators blocked roads in Beirut, the Bekaa Valley and near the southern city of Sidon on Tuesday in protest at the road closure affecting Arsal. A Reuters photographer said a bystander was shot dead during a protest in a Sunni district of Beirut. The source of the gunfire was not immediately clear. (Reporting By Stephen Kalin and Alexander Dziadosz; Editing by Angus MacSwan)