Putin, whose term in office ends next month, called the meeting "positive", but the main issues behind the frayed relations between Russia and the alliance remained unresolved.

'Direct threat'

On Thursday, Nato refused to grant the former Soviet states of Ukraine and Georgia a roadmap to membership at the moment, but did promise to incorporate them into the bloc in the future.

"A powerful bloc at our borders will be seen by Russia as a direct threat to our security," Putin told journalists.

"I heard them saying today that the expansion is not directed against Russia. But it's the potential, not intentions, that matters"

Vladimir Putin, Russia's president
"I heard them saying today that the expansion is not directed against Russia. But it's the potential, not intentions, that matters."

Despite strong US backing to bring in Ukraine and Georgia, Germany, France and some other alliance members opposed the move, fearing that it would provoke Moscow.

Jaap de Hoop Scheffer, Nato secretary-general, sought to reassure the two nations on Friday that there was "not a sliver of a doubt" they would join the alliance before long.

"It is true that Nato enlargement is a contentious issue. The minds do not exactly meet, to put it mildly." 

He described the talks with Putin as "frank and open", but conceded that there were no major breakthroughs.

However, Russia did agree to allow Nato to use Russian land to deliver non-lethal supplies to alliance troops in Afghanistan, but not troops or air transit arrangements as initially sought by the military alliance.

A Nato spokeswoman said non-lethal supplies covered everything from food to certain military equipment. She did not say why troops or air transit would not be covered.

Missile shield

Putin said he had been encouraged that the United States had listened to Russian concerns about its planned US missile shield system to be deployed in the Czech Republic and Poland and said discussions would continue.

"What is positive in today's dialogue is that our concerns about ensuring our own security ... have been heard," he said. 

Putin will meet George Bush, the US president, at his Black Sea retreat in Sochi this weekend for talks expected to focus on the missile defence system.

Condoleezza Rice, the US secretary of state, said that the two leaders were expected to produce "a strategic framework" to guide relations between Washington and Moscow under their successors.

Alan Fisher, Al Jazeera's correspondent in Bucharest, said: "Vladimir Putin was very clear there are some stark differences between Nato and Russia.

"But he also made it clear there is no reason why Nato and Russia cannot co-operate on the missile defence system."