US presidential candidate Barack Obama, wrapping up an overseas tour where he got a rock star reception, defended his decision to take the trip despite mixed signals about its impact on his popularity at home.

"I am convinced that many of the issues we face at home are not going to be solved as effectively unless we have strong partners abroad," he told reporters in London yesterday after meeting British Prime Minister Gordon Brown.

"This was important for me not only to try to highlight or amplify how the international situation affects our economy back home but also hopefully to give people at home, but also leaders abroad, some sense of where an Obama administration might take our foreign policy."

Obama said he spoke with Brown on topics ranging from the Middle East to climate change, terrorism and financial markets.

The two men spent more than two hours together, first chatting on the patio of 10 Downing Street and during a brief stroll together in a tourist area nearby.

Obama, a Democrat who is running against Republican John McCain in the November 4 US election, has been on a seven-nation overseas tour that began in Iraq and Afghanistan and included Israel, Jordan and Kuwait as well as Europe.

He aims to burnish his foreign policy credentials and counter McCain's criticism that he lacks experience.

A daily tracking poll from Gallup published on Friday showed Obama with a six-point lead over McCain, close to the lead he has held over his Republican rival for the past several weeks.

In Europe, Obama is hugely popular with his early opposition to the invasion of Iraq accounting for part of the appeal. He has called for a refocusing of US efforts on Afghanistan and an end to the Iraq war.

Obama talked of his proposal to add more troops in Afghanistan and said, in reference to his call for Europe to increase its contribution there, "Obviously we'd like some of that burden shared."

Outside 10 Downing Street some British fans of his chanted Obama's campaign mantra: "Yes, we can."

"He's a godsend," gushed Lucien Senna, 39, who, like Obama, is black, and said she felt his rise signalled America was moving beyond its racial divisions of the past.

But the London stop, the last one before Obama heads home to Chicago, was more low-key than earlier legs of his trip.

In Berlin, Obama drew a crowd of 200,000 people to an outdoor speech and he elicited effusive praise from French President Nicolas Sarkozy at the Elysee Palace in Paris.

Still unclear is the reaction among US voters, whom Obama acknowledges are worried about gas prices and home foreclosures.