DONETSK, Ukraine — Separatists fighting the Kiev government claimed credit for shooting down two warplanes Wednesday over eastern Ukraine near where a passenger airliner crashed last week after being struck by a missile.

The attack on the warplanes came just six days after the Malaysia Airlines disaster, which has drawn international outrage and showcased the advanced firepower that apparently is available on the ground in the region. The Ukrainian military said Wednesday that the two planes were flying at nearly 17,000 feet – an altitude that is out of the reach of the shoulder-fired missiles that the rebels said they had used to down the jets. Neither the government’s nor the rebels’ claims could be verified.

Ukraine has accused Russia of supplying fresh firepower to rebels over the porous border in recent days, even as international attention has focused on a possible Russian role in the attack on Malaysia Airlines Flight 17. Although the details of Wednesday’s incident remained unclear, it was a sign that the rebels are able to inflict significant damage on the Ukrainian military, whose major advantage over its rivals is in the air.

The pilots of the two SU-25 jets, which were among four planes that were fired upon as they were returning from a mission near the Russian border, are thought to have bailed out over rebel-held territory. Their condition and whereabouts are unknown, and the rebels said they had initiated a search mission.

“We shot them down with MANPADS,” said rebel spokesman Sergey Kavtaradze, referring to shoulder-mounted missiles that can reach only a limited altitude.

Andriy Lysenko, a spokesman for Ukraine’s National Security and Defense Council, told reporters in Kiev that the planes were flying too high to be hit by such a weapon, though.

Lysenko alleged that the missiles that hit the two planes were fired from Russian territory.

“They were shot down very professionally. The terrorists do not have such professionals,” he said in reference to the pro-Russian rebels.

Photos that have emerged since the Flight 17 crash last Thursday suggest that Buk missile launchers that apparently were in the rebels’ possession – and one of which Ukraine said was used to down the jetliner – have been transported to Russia. But U.S. officials have said that tanks, rocket launchers and other arms continue to flow into Ukraine from Russia.