* Two young men from Spain fighting with pro-Russians
* Russians, Chechens, Ossetians, Serbs fight in rebel ranks
* Russia says Europeans fighting in pro-Kiev units
By Kazbek Basayev
DONETSK, Ukraine, Aug 8 (Reuters) - Angel Davilla-Rivas, a Spaniard who came to east Ukraine to fight alongside pro-Russian rebels, proudly shows off two big monochrome portraits of Soviet leaders Vladimir Lenin and Joseph Stalin, tattooed on the right and left side of his torso.
Davilla-Rivas and his comrade Rafa Munez, both in their mid-twenties, travelled by train from Madrid to eastern Ukraine where they joined the Vostok battalion, the most prominent and heavily armed unit fighting Ukrainian troops.
"I am the only son, and it hurts my mother and father and my family a lot that I am putting myself at risk. But ... I can't sleep in my bed knowing what's going on here," said Davilla-Rivas, sporting a cap with the Soviet red star pinned to it.
That star and a ribbon around Munez's wrist hint at the Spaniards' motivation for joining a war thousands of miles from home.
The ribbon's red, yellow and purple are the colours of the Republicans in the Spanish Civil War, a conflict in the 1930s where thousands of foreigners joined the leftists against right-wing foes who eventually prevailed.
Angel said he wanted to return the favour after the Soviet Union, under Stalin, supported the Republican side in Spain.
More than 1,100 people have been killed in the fighting in Ukraine since mid-April, according to the United Nations, in a civil conflict that has dragged ties between Russia and the West to their lowest since the Cold War.
The Spaniards are not the first foreigners to enter the fight.
Men from Russia, its former rebel republic of Chechnya and the Caucasus region of North Ossetia have fought on the rebel side along with volunteers from a Russian-backed separatist enclave of Georgia and natives of Serbia.
Russians have also taken top positions among the rebels, though a local took over at the helm of the self-proclaimed "Donetsk Peoples' Republic" on Thursday, in a move aimed at blunting Western accusations the rebellion is run by Moscow.
Moscow said last month there were reports that citizens from Sweden, Finland, France and the former Soviet Baltic states had joined pro-Kiev volunteer battalions in the east as "mercenaries".
Davilla-Rivas blamed the West - which has imposed sanctions on Moscow, accusing it of backing the rebels - for stoking the war.
"The United States is trying to provoke a third (world war) against Russia here with your people," he said.
"Ordinary people are suffering because they are caught in between three imperial powers - the Russian Federation, the European Union and, certainly, the United States, which is putting money into all this."
A Vostok fighter said he was happy to have the Spaniards.
"We need support now, we need fighters. An additional automatic gun will do no harm, to support, to cover one's back," said the young, brown-haired man who did not give his name.
The Spanish embassy in Moscow was not immediately available for comment. (Writing by Gabriela Baczynska; Editing by Robin Pomeroy)