DHAKA: Russian aircraft carrying nearly 2,000 suspected troops have landed at a military airbase near the regional capital of the restive Crimean peninsula, a top Ukrainian official has said, accusing Moscow of an "armed invasion".

"Thirteen Russian aircraft landed at the airport of Gvardeyskoye [near the city of Simferopol] with 150 people in each one," Sergiy Kunitsyn, the Ukrainian president`s special representative in Crimea, told the local ATR television channel on Friday.

He also said that the airspace had been closed when the deployment happened.

Speaking on Friday, Barack Obama, the US president, said he was "deeply concerned" at the reports of the troop movements.

Obama said: "Any violation of Ukraine`s sovereignty would be deeply disturbing."

Obama and European leaders would consider skipping a G8 summit in Sochi, Russia, planned for this summer if Russia intervenes militarily in Ukraine, a senior US official said on Friday.

The senior official, speaking on condition of anonymity, said the US is consulting with its European partners on
potential costs that might be imposed on Russia for any Ukraine intervention.

US officials told the Reuters news agency that Washington has seen indications of troop movements from and into Crimea, but their numbers are unclear, as are the intentions of those movements.

The official said Washington`s response could also include withholding deeper trade and commerce ties that Moscow is seeking.

BDST: 0951 HRS, MAR 01, 2014