There is a "real and present danger" of Russia trying to destabilise the Baltic states of Latvia, Lithuania and Estonia, the UK defence secretary says.

Michael Fallon said he was worried about "pressure" from Russian President Vladimir Putin on the ex-Soviet states, which are Nato members.

Russia might use tactics there similar to those it used in Ukraine, he said.

Mr Fallon said Nato must be ready for aggression from Russia "in whatever form it takes".

"Nato is getting ready," he added.

His comments came after Prime Minister David Cameron called on Europe to tell Russia it faced economic and financial consequences for "many years to come" if it did not stop destabilising Ukraine.

Speaking to journalists from the Times and Daily Telegraph during a flight to Sierra Leone, where British troops are helping tackle the Ebola outbreak, Mr Fallon said: "I'm worried about Putin.

"I'm worried about his pressure on the Baltics, the way he is testing Nato."

He said Russia was likely to use covert tactics like those he said it used to annex Crimea and in the current Ukraine conflict.

Russia has denied helping pro-Russian separatists, but it has been repeatedly accused of sending weapons and troops and using propaganda to inflame tensions.