Image copyright EPA

David Cameron is holding talks with German Chancellor Angela Merkel on Britain's EU reform aims, the situation in Syria and the migrant crisis.

The prime minister has invited his German counterpart for a working dinner at his country residence, Chequers.

The wide-ranging talks also cover the threat of so-called Islamic State, the situation in Iraq and Ukraine.

Mr Cameron earlier welcomed Estonian Prime Minister Taavi Roivas to Downing Street for bilateral talks.

'Grave situation'

A Number 10 spokesman said: "The prime minister is hosting Chancellor Merkel at Chequers for bilateral talks on EU reform, Syria, Ukraine and relations with Russia.

"The meeting begin with a lengthy, in-depth discussion on Syria, particularly the terrorist threat from [the Islamic State group] and the need for a political solution to the conflict.

"Talks then moved on to the situation in Ukraine and Russia's behaviour. They agreed that the EU must maintain sanctions on Russia until the Minsk agreement is fully implemented.

"Over dinner, they are expected to discuss the UK renegotiation of its relationship with the EU, taking stock of the technical talks that have taken place since July and looking ahead to the process between now and the December European Council."

Image copyright EPA Image caption Mr Cameron and the Estonian PM discussed the UK's EU renegotiation aims and the migration crisis

The meetings with his European counterparts come as a new campaign to get the UK to leave the European Union is launched, ahead of the in-out referendum, promised by 2017.

Vote Leave, made up of Conservative, Labour and UKIP MPs and donors, says it wants to negotiate a new deal based on free trade and friendly co-operation.

During talks with the PM at Downing Street, Estonian Prime Minister Mr Roivas thanked Mr Cameron for the UK's commitment to send 100 British military personnel to the Baltic region.

Defence Secretary Michael Fallon has said the troops will deter Russian aggression beyond Ukraine and reassure eastern European Nato members.

Image copyright PA Image caption Michael Fallon (L) held talks with his US counterpart

Speaking at a press conference on Friday, Mr Fallon - who held talks with his US counterpart Ash Carter in London - said the UK government was committed to building support for air strikes against IS in Syria.

He said Russia's military action had made a "grave situation even worse".

The UK is currently involved in coalition air strikes against Islamic State targets in Iraq but not Syria, after Parliament voted against the move in 2013.