It is time for Canada to be ejected from the Group of Eight, Bill Emmott, former editor of the Economist, mischievously suggests in his recent book. That would help make room for Asia's two emerging giants, without whom, he contends, no serious global discussion can now be held.

Put to a Canadian, such talk may elicit reminders of that country's pivotal influence as a potash, tar sands and uranium producer. But to many neutral observers, a club of the world's leading nations is starting to look hollow without China - the fourth-largest economy in dollar terms, according to the World Bank. (By pure gross domestic product reckonings, India would be included only in a G12.)

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Take this year's summit, where global warming tops the agenda. China has surpassed the US as the world's biggest carbon emitter and India is fast climbing the rankings. That is why those two, plus others such as Brazil and Indonesia, have been invited to outreach groups on Wednesday, set aside to discuss climate change.

High oil and food prices, too, cannot be sensibly debated without China, whose ravenous appetite for hydrocarbons and other commodities is bloating demand. Biofuels, another pressing topic, might be more sensibly discussed if Brazil, a big producer, were present. Monday's talks about African development could feel incomplete without a briefing from China on its galloping ambitions there.

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Masaharu Kohno, deputy minister of foreign affairs and Japan's chief sherpa, says: "All the main issues are trans-border issues, be it terrorism, the food crisis or climate change. We are no longer in an era where we can be bound by national borders."

Tony Blair, the former British prime minister, says: "It is important if the G8 is to have a strong role in the future to recognise the importance of China, India and Brazil. Quite how you achieve that institutionally is a different question."

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Clement Adibe, professor of political science at Chicago's DePaul University, says that when the group - at the time the G6 of the US, the UK, West Germany, France, Italy and Japan - first met in Rambouillet, France, 33 years ago, it was to discuss the rich world's response to the oil shock. "In 1975, the G8 came out to promote its own interests, those of advanced countries," he says. "Now things have moved beyond that. But it is hard for the G8 to shake off its elitist baggage."

Some G8 members, not least Japan, the host, are wary of messing with the formula, which is designed to promote intimacy and candour. Tokyo, with neither a permanent seat on the United Nations Security Council nor Nato membership, jealously guards its opportunity to sit at the top table - all the more so if it is suggested it share that privilege with arch-rival China.

"We cherish this format of G8. It is a very comfortable one for us," says a foreign ministry official. "The G8 is the G8. But some issues can be discussed with other nations like China and India . I think the outreach format is adequate for that," he says of the ad hoc, bolt-on meetings that will be held with a record number of countries this year.

Andrew Cooper, associate director of the Centre for International Governance Innovation in Ontario, says that the G8 must decide whether it wants to be a club of democracies with common values - in which case whither Russia? - or whether seats should be allotted on the basis of influence. If the latter is the guiding principle, he says, then China must be in.

But he points out: "This is not just a question for the G8 but a question for China as well."

Indeed, Beijing is ambivalent. On the one hand, it craves the recognition of its new-found status and wants to avoid being labelled as a hindrance to international institutions. On the other, it is wary of being bound by international agreements on such topics as carbon emissions or foreign ex­change policy.

Even if the G8 leaders were to vote this week to offer Canada's place to China, it is by no means certain that Beijing would accept.

Media links and security drive up price tag

As with all the most exclusive clubs, Group of Eight membership does not come cheap, writes David Pilling in Rusutsu, Japan.

The Japanese government estimates that the price tag for the three-day lakeside summit and a marathon of lead-up ministerial meetings will run to Y60.6bn ($570m, euro361m, pound286m). Inevitably, such large sums prompt a flurry of calculations from charities and development agencies to show how the money could have been better spent.

Tomohiko Taniguchi, the deputy press secretary at the foreign ministry, said Y30.7bn was for the national police agency, at least 21,000 of whom have been mobilised from all regions of Japan, put up in hotels and paid overtime.

Other big-ticket expenses include paying for the coastguard to patrol waters off Japan and the leasing of a specially constructed media centre with high-speed telecommunications links to the Windsor hotel, where G8 leaders will meet.

Mr Taniguchi said costs were high because of the threat of terrorism. Japan had also taken extensive measures to prevent a repeat of the activist protests that disrupted previous summits, including last year's in Heiligendamm, he said.

Nevertheless, the bill for this year's event will be cheaper than the Y81.5bn spent when Japan hosted the G8 in Okinawa eight years ago. The cost of that summit, a record, was heavily criticised, particularly since aid to Africa was a big part of talks. Japan defen­ded the cost, saying it included infrastructure for the underdeveloped island that would have been built anyway.

John Kurton, director of the G8 research group at Toronto University, said it was almost impossible to compare the cost of hosting summits because of differing accounting methods. The cost of Toyako is estimated at roughly three times that of Gleneagles in 2005. He said that for resort areas like Toyako, the investment was paid back many times in free publicity. "It will forever be the place where the G8 leaders met," he said.

Hoteliers have been complaining though that, this year at least, bookings are substantially down as tourists avoid a once tranquil wilderness now crawling with security and delegates.

Additional reporting by Geoff Dyer in Beijing