* Rebels shot down military plane, killing 49 servicemen
* President declares Sunday a day of mourning, vows response
* Kiev sombre, eastern city of Donetsk ignores mourning
By Timothy Heritage and Alessandra Prentice
KIEV/DONETSK, Ukraine, June 15 (Reuters) - Church bells rang out over Kiev's Maidan square and hundreds of mourners bowed their heads in silence on Sunday, a national day of mourning, to honour 49 Ukrainian servicemen killed by pro-Russian separatists.
But some 600 km (375 miles) away to the east in the city of Donetsk, heart of an armed insurgency against central rule by Kiev, there were few signs of mourning as people enjoyed a lazy stroll, sipped coffee in cafes and watched their children play.
Few events illustrate more clearly the bitter chasm that has opened up between east Ukraine and the rest of the country of 45 million. Heroes to some, the 49 killed when a missile hit their plane on Saturday were enemies to others.
"I feel desperate, like it's a betrayal. I don't know what I can do to help," Volodymyr Radchenko, an engineer in his fifties, said on the Maidan, cradle of an uprising which ousted Ukraine's Moscow-backed president in February.
Nearby, an Orthodox priest led prayers on a stage, flanked by men in black masks and camouflage fatigues.
Radchenko's depressed mood and sense of helplessness are shared by many in Kiev, whose euphoria over Viktor Yanukovich's overthrow as president has given way to dismay as Russia annexed Crimea in March and separatists rose up in the east in April.
"I'm very worried," said choreographer Iryna Zhadan, starting to weep. "I cry and pray a lot for the dead soldiers."
WORRIES ABOUT THE FUTURE
More than 100 protesters were killed in clashes on and around the Maidan before their hate figure, Yanukovich, fell. Makeshift shrines have been erected around the square and some protesters are still camping out on its edges, worried about the fragile peace and the direction the country is taking.
Ukraine now has a pro-European leadership and a new president, Petro Poroshenko, who has intensified a military campaign in the east since being elected on May 25 but has also launched tentative peace talks with a Russian envoy.
He has promised a tough response to the shooting down of the plane which some say is needed to crush the separatists but others fear could lead to all-out war with rebels armed with tanks which Kiev and Washington say come from Russia.
Moscow denies backing the rebels. Facing the possibility of further Western sanctions, it disavows any plan for a military invasion to absorb mainly Russian-speaking eastern Ukraine.
But some Ukrainians still fear Russia and the West could fight a proxy war in Ukraine and would rather let the rebellious regions of Donetsk and Luhansk go than face such a conflict.
"It's awful. I just don't understand why we need Donetsk and Luhansk," said Lyudmila Shevchenko, a 60-year-old Kiev resident. "If they like it without us, let them live on their own and we won't send our children to their deaths."
The downing of the military plane as it came in to land at the airport outside Luhansk killed more government servicemen than any other incident since the conflict began.
It has increased tension as Moscow and Kiev try to agree how much Ukraine should pay for Russian gas before a Monday deadline for Kiev to pay $1.95 billion in debts or have its gas cut off, that could disrupt flows to the rest of Europe.
It also fuelled a violent protest at the Russian embassy in Kiev and a diplomatic spat over insulting comments by Ukraine's foreign minister about President Vladimir Putin.
EAST DOES NOT MOURN
But few sympathisers could be found in east Ukraine, where leaders of the self-proclaimed Donetsk People's Republic (DPR) ignored Poroshenko's call for a day of mourning and did not arrange a minute's silence to remember the victims.
"We could hold a day of mourning every day for the children and ordinary citizens who are dead because of the Ukrainians," a DPR spokesman said. "In Kiev they're mourning the deaths of soldiers who were coming here to kill innocent people - it's unbelievable ... If they don't want soldiers to die, they shouldn't have violated Luhansk airspace."
In Donetsk, an industrial hub of one million people, there was as much discussion of the soccer World Cup in Brazil as of the shooting down of the plane. Many regard the Anti-Terrorist Operation, stepped up by Poroshenko, as driving a deeper rift between Ukrainians.
"They wanted a war, now they can have it. War brings casualties and they have to face that," said Zina Demyanova, 60, an accountant.
Sergei, a 35-year-old waiter, described the downing of the plane as a "legitimate military victory".
"I'm not sorry. I'm not mourning. We wanted to be acknowledged (by Kiev), the east (of Ukraine) wanted only that, and they sent their killers instead," he said.
A retired administrative clerk who gave her name only as Iryna was among the few questioned by Reuters in the east who said openly they regretted the loss of life on both sides.
"This (war) is nonsense, murder. I was crying last night and I cry every day ever since this madness started because all these people have mothers and families and children," she said.
Others suggest few people are prepared to speak out against the rebels in the east because they are afraid.
"It's a horrible day and I am honestly mourning. They killed 49 people in cold blood, people who came to protect their country from this backward lot," said a student who gave her name only as Svetlana.
"You know, there are people in Donbass (the coal mining area of east Ukraine) who do not support this madhouse here and we are begging Kiev to rescue us." (Additional reporting by Aleksandar Vasovic in Donetsk and by Natalia Zinets, Pavel Polityuk and Margarita Chornokondratenko in Kiev, Writing by Timothy Heritage; Editing by Gareth Jones)