U.S., UK Says Russia 'Humanitarian' Push into Ukraine Would Be Illegal

Any "humanitarian" mission by Russia into Ukraine would be "unjustified and illegal", U.S. President Barack Obama and British Prime Minister David Cameron agreed during a telephone call Saturday, Downing Street said.

"On Ukraine, both expressed grave concern about reports that Russian military vehicles have crossed the border into Ukraine and that Russian armed forces are exercising for a 'humanitarian intervention,'" a statement from Cameron's office said.

"The Prime Minister and President are absolutely clear that such a so-called humanitarian mission would be unjustified and illegal."

Russia has denied allegations by Kiev that it tried to send a convoy, including troops and military hardware, towards the border with eastern Ukraine under the guise of a humanitarian mission.