BAKCHISARAY, Ukraine (Reuters) - Bearded men in camouflage uniforms and black fur hats and armed with knives, were checking traffic on Thursday along the busy road linking Crimea's regional capital of Simferopol and the naval port of Sevastopol.

A black flag with a skull, the standard of Serbian nationalists, and a Serbian national flag fluttered in the wind alongside the Russian tricolour, bringing back images from the turbulent events of the 1990s in the Balkans.

Bratislav Zivkovic, one of the commanders of Serbia's Chetnik movement, an ultranationalist group with roots in another era, said it was only natural for them to come to Crimea to help their Russian brethren.

Crimea, part of independent post-Soviet Ukraine since 1991, has been in the grip of the Russian military for a week. Its local assembly has declared that the region wants to become part of Russia, subject to a referendum scheduled for Sunday.

Zivkovic's group of five activists have been tasked with manning patrols alongside Cossacks, most of whom have journeyed to the peninsula from Russia in anticipation of the referendum.

"Our motive was to offer moral support to the Russian people of the Crimea and their right for a referendum and nothing more than that," said Zivkovic. "Through the centuries, Russians were helping us, they were giving us support, even now in Kosovo, so we came here to support them."

Russia is Serbia's traditional ally as the two nations share the same Slav origins, Orthodox Christian faith and similar languages. Serbia is also heavily dependent on Russia's energy and the cash-strapped government in Belgrade has turned to Kremlin to underpin its budget.

The Serbian Chetniks draw their name and traditions from insurgents who fought Ottoman Turks in 19th and early 20th centuries. They gained notoriety in the 1990s, when their units committed atrocities against non-Serbs in Croatia, Bosnia and Kosovo, a former Serbian province dominated by ethnic Albanians which won independence in 2008.

Roadblocks were erected along key roads in Crimea last week when men in green uniforms, bearing no national insignia, appeared outside Ukrainian bases, taking control of naval and military installations in the peninsula.

SERBS, COSSACKS ON PATROL

The checkpoint manned by Zivkovic's men was also controlled by masked men in camouflage fatigues armed with shotguns, who described themselves as Cossacks. A group of policemen in Ukrainian uniforms, all carrying machine guns, stood aside, ceding control to the Serbian volunteers and Cossacks.

Zivkovic said his men were willing to fight to ensure the peninsula's ethnic Russian majority won the right to secede and join Russia. But they were there, he said, to prevent violence.

"Every possible incident that might occur will be extinguished swiftly," he said. "We are hoping that even if it comes to fighting and armed conflict, it will be very short, because the population is Russian and the peninsula is Russian."

As the queue of cars and trucks approaching the checkpoint lengthened, one middle-aged truck driver, who identified himself only as Oleg, said he was gratified by Serbian solidarity.

"This is great. They are helping the guys," he said. "This is how it should be. We have to help each other."

Others were angry.

"Who are they helping? I don't understand that. I don't need any help, no one is bothering me here," said Denis, a driver from Simferopol.

"The (Serbs) are occupiers, genuine occupiers. I have no other names for them," said Asan, another driver.

(Editing by Ron Popeski)