Mr Brown told lawmakers on Wednesday that President-elect Barack Obamahas said he will attend the talks.

The G-20 nations and four international organisations met for emergency talks in Washington on Nov 14-15.

Leaders said they needed a summit early next year to check progress on promises to cooperate more closely, toughen supervision of banks and give bigger roles to fast-rising nations.

The London talks will come ahead of NATO's 60th anniversary summit on April 3-4, being held jointly by the neighboring cities of Strasbourg, in France, and Kehl, Germany.

Leaders of the bloc's member nations are expected to attend, including Mr Brown and Mr Obama. Brown's Downing Street office said that leaders plan to travel directly from the financial talks in London to the NATO summit.

Included in the G-20 are Argentina, Australia, Brazil, Britain, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea, Turkey and the United States. The 27-nation European Union bloc is also a member of the grouping.

At the Washington talks, Spain and organisations like the World Bank and International Monetary Fund also took part in discussions.

Leaders also endorsed a series of broad goals to fend off future economic calamities and to revive the world economy.

They called for intensified government efforts at bolstering national economies, cooperation on international regulation of the financial system and reform of global structures to aid needy developing countries. -- AP