Reports of a planned "humanitarian intervention" in Ukraine by Russian armed forces have been met with "grave concern" by the Prime Minister and US President, Downing Street says.
Any such move would be "unjustified and illegal" and would prompt "further and tougher sanctions", the two leaders were said to have agreed in a telephone call.
"They reiterated that we continue to urge Russia to engage with the international community and the Ukrainian government to find a political solution to the crisis," a Number 10 readout of this afternoon's call said.
More top news
Angela Merkel looks set to extend her 12 year stay as the German Chancellor, an election poll from the country's general election suggests.
Police have foiled seven terror attacks since the Westminster atrocity in March, London Mayor Sadiq Khan has revealed.
Cumbria Police have been forced to rescue a group of hikers from a mountain who were unable to walk after consuming cannabis.