Media playback is unsupported on your device Media caption Watch two of the jets take off from RAF Coningsby. in Lincolnshire

Four RAF Typhoons will leave their base in Lincolnshire later for Lithuania to help carry out Nato's air policing role of the Baltic states.

The Typhoons and six Polish jets will take over from a US squadron to patrol the alliance's eastern flanks.

The long-standing rotation of Nato military jets in Lithuania has recently been stepped up in response to rising tensions with Russia over Ukraine.

The UK government said the move would provide reassurance to Nato allies.

The Typhoons will leave their base at RAF Coningsby on Monday morning and be joined by more than 100 RAF support staff in Lithuania.

Heightened concern

Only last week Typhoons based at RAF Leuchars in Fife intercepted two Russian bombers flying in international airspace off Scotland.

The jets were sent to investigate the Russian planes which are understood to have turned away shortly afterwards.

The MoD said fighter planes were scrambled to similar incidents eight times last year.

The Typhoons' role over the Baltic states, which rely on Nato for fast jet support, will be similar.

Defence Secretary Philip Hammond said the RAF fighters would provide reassurance to Nato allies at a time of heightened concern about Russia whose jets, the Pentagon has said, have already encroached into Ukraine's airspace.

Last month, Mr Hammond told the Commons that the status of Ukraine was "quite different" from that of Nato countries.

He said: "Nato countries enjoy the Article 5 guarantee which protects and assures their security, but we are doing everything we can to reassure our Nato allies about the protection we offer."

"I am able to advise the House we have taken the decision to offer to Nato UK Typhoon aircraft to augment the Polish contribution to the Nato Baltic air policing mission."

Planned exercise

Later this week about 100 British troops will travel to Estonia to take part in a multi-national military exercise.

The Ministry of Defence said this had been planned for some time.

In Ukraine, pro-Russian separatists in the east of the country have released one of a team of eight European monitors seized in the flashpoint city of Sloviansk.

The officer, a Swede, was freed on medical grounds, it has been confirmed.

The monitors were shown to the media on Sunday - a move described as "revolting" by Germany, the native country of four of the team.

The remaining seven are still being held and diplomacy continues to try to secure their freedom.