The announcement came within hours of a hopeful announcement: Pakistan and India have both agreed to resume talks in the coming weeks. Both countries have also agreed to put a moratorium on nuclear tests.
Meanwhile, at the G8 conference, U.S. Secretary of State Madeleine Albright, ministers from Japan, Russia, Britain, France, Germany, Italy and Canada had agreed to use their votes in international financial institutions to delay consideration of such loans.
The Big Five established nuclear powers hoped to build a wider coalition to defuse a looming arms race between India and Pakistan after their tit-for-tat atomic tests.
British officials said the Group of Eight meeting would be joined for an informal lunch by ministers or representatives from China - the fifth nuclear weapon state - and from Argentina, Brazil, South Africa, Ukraine, and the Philippines.
Argentina, Brazil, South Africa, and Ukraine have all renounced nuclear weapons in the last decade, while the Philippines, coordinator of the ASEAN regional forum, will be representing Asian countries concerned over the threat of regional tension.
EU Commission vice president Sir Leon Brittan joined the talks, which are a follow-up to a meeting of the Big Five foreign ministers in Geneva last week that urged New Delhi and Islamabad to stop testing and start talking.
"The aim is to widen the coalition of countries to win India and Pakistan round to dialogue," a British Foreign Office spokesman said.
India carried out a series of nuclear tests in May, and was followed by Pakistan, which ignored international appeals not to follow suit.
The U.N. Security Council, backing the conclusions of the nuclear-armed permanent members, told India and Pakistan that neither country could join them as nuclear weapon states under the Nonproliferation Treaty.
The London meeting was likely to urge dialogue over Kashmir, the long-standing dispute that Pakistan wants to put on the international agenda while India refuses.
Pakistan's foreign minister said Thursday that the dispute with India over Kashmir could trigger an Indo-Pakistani nuclear war "at any time."
"Occupied Kashmir today constitutes the world's only flashpoint, the major flashpoint," Gohar Ayub said in an interview.