U.S. President Barack Obama arrived here on Tuesday for the Group of 20 (G20) summit to discuss ways to alleviate the global financial and economic crisis.
The summit is scheduled to begin at the Excel Center in London's Docklands on Thursday.
Obama and other world leaders are expected to agree to a major revamp of the world financial system as well as new coordinated measures to combat the economic downturn.
On the sideline of the G20 summit, Obama is scheduled to hold bilateral talks with British Prime Minister Gordon Brown.
He will also meet with Chinese President Hu Jintao and Russian President Dmitry Medvedev.
The G20 summit, convened against the backdrop of a deepening global recession, has been seen as the first opportunity for major world leaders to meet the new U.S. president, who was sworn into office on Jan. 20.
The outcome of the summit, however, rests with participants' ability to bridge their differences on economic stimulus plans and reforming the global financial system.
While the White House has pushed for more fiscal measures to help the economy, major European countries remain skeptical about this, and they mainly focus on enhancing financial regulation and reforming the world financial system.
Major developing countries also support reforming the world financial system, but they insist that they should have more say in any new financial order.
In an interview published by Financial Times on Sunday, Obama called on G20 leaders to "deliver a strong message of unity in the face of crisis."
He also played down differences with European leaders over the need for more economic stimulus and a new financial regulatory system.
"We need stimulus and we need regulation. We need to deal with the problems right in front of us and we also need to make sure we are taking steps to prevent these types of breakdown from happening again," he said.
After the one-day G20 meeting, the U.S. president will travel to the French-German border for a NATO summit. Then he will head for the Czech Republic and Turkey.
This is Obama's first major trip abroad since his inauguration.