A U.S. senator detained for three hours in a Russian airport while officials refused to let the U.S. military flight take off said Monday that he had received no explanation for the delay, but welcomed the Russian government's apparent apology, AP reported. Sens. Richard Lugar, an Indiana Republican and chairman of the Senate Foreign Relations Committee, and Barack Obama, an Illinois Democrat, were delayed for three hours at an airport in Russia's Ural Mountain city of Perm on Sunday. Russian border officials demanded that they be allowed to inspect the U.S. plane, but were refused by the Americans. Eventually allowed to leave, the U.S. senators arrived late Sunday in the Ukrainian capital. «We are not certain as to why or the particular activity that caused that delay,» Lugar said, speaking briefly to journalists in the Ukrainian parliament. «We are pleased that our flight was able to continue to Kiev, albeit three hours later.» He said U.S. Embassy officials informed the senators that «an official at the Foreign Ministry has issued an apology this morning.» The Russian Foreign Ministry said it could not confirm or deny the apology. The U.S Embassy could not confirm the information immediately. --mor 1410 Local Time 1110 GMT