NATO members meeting in south Wales have agreed to reverse the trend of declining defence budgets, the alliance's secretary general Anders Fogh Rasmussen has announced.

Mr Rasmussen was speaking at the end of a two-day summit at which the UK has pressed all members of the 28-strong alliance to meet the Nato target of spending 2% of gross domestic product (GDP) on defence.

As the conference drew to an end, Ukraine's president Petro Poroshenko - who has attended the gathering as a Nato partner - confirmed that a deal had been signed by Ukraine and Russian-backed rebels for a ceasefire, due to begin this afternoon.

Mr Rasmussen said the goal of peace and security in Europe had been endangered by Russia's illegal annexation of Crimea and aggression in the east of Ukraine, as well as by the spread of violence and extremism in north Africa and the Middle East.

He said Nato members had made a pledge "to reverse the trend of declining budgets and raise them over the coming decade" and to "move towards the Nato guideline of spending 2% of GDP on defence".

Mr Rasmussen said progress towards meeting the pledge would be reviewed at every future Nato summit.

"This is no easy task, and there is much work to do," he said.

"But the direction of travel is clear and the security of our countries of citizens is too important for us to cut corners or to cut still more funds."

Mr Rasmussen also confirmed that the alliance has agreed to establish a new high-readiness "spearhead" force able to deploy thousands of troops in a matter of days.

The alliance is also preparing to "pre-position" supplies of fuel and ammunition in bases in eastern Europe, in moves designed to counter the threat of Russian aggression and provide reassurance to Nato members Estonia, Latvia and Lithuania.

"This decision sends a clear message - Nato protects all allies at all times," said Mr Rasmussen.

"It sends a clear message to any potential aggressor: should you even think of attacking an ally, you will be facing the whole alliance."