Rebels in conflict-wracked eastern Ukraine claimed responsibility for the downing of a military transport plane on Monday along the country's eastern border with Russia, after Kiev voiced suspicion that the aircraft was "likely" shot down from Russia.

The self-styled leader of the "People's Front" in Luhansk region, Alexei Chmilenko, claimed that his fighters shot down the Antonov-26 in a retaliation for the airstrikes against rebels by the Ukrainian troops.

"We have enough armaments now that are needed to shoot down such an aircraft. One doesn't need any of the latest high- precision weapons to shoot it down. It was not a hard task for our forces at all," Interfax news agency quoted Chmilenko as saying.

Earlier in the day, a Ukrainian military spokesman said they had lost contact with an Antonov-26 aircraft near Luhansk in the restive eastern regions, where Ukrainian troops were battling with insurgents.

Ukraine's military spokesman Vladislav Seleznyov said the aircraft, with eight people on board, was on its way to a checkpoint when it was shot down.

Later, the Ukrainian presidency said that "Crew members from an AN-26 plane... that was shot down have established contact with the general staff," without giving further details on the whereabouts of the eight people on board.

The transport plane had been flying too high to be hit by portable missile systems used by the rebels, signaling that the shots had come "likely from the territory of the Russian Federation," the presidency said in a statement posted on its website.

The press office of the self-proclaimed Luhansk People's Republic earlier announced that four crewmembers were taken as prisoners.

"The captives are detained and being questioned in the city of Krasnodon now," Interfax news agency quoted the press office as saying.

Fierce fighting and heavy casualties have been reported since the government forces resumed military operations against insurgents in early this month.