GENEVA — World trade talks collapsed here on Tuesday after seven years of on-again, off-again negotiations, in the latest sign of India's and China's growing might on the world stage and the decreasing ability of the United States to impose its will globally.

Pascal Lamy, director-general of the World Trade Organization, failed to bridge differences between a group of newly confident developing nations and established Western economic powers. In the end, too few of the real power brokers proved committed enough to make compromises necessary to deliver a deal.

The failure appeared to end, for the near term at least, any hopes of a global deal to further open markets, cut farm subsidies and strengthen the international trading system.

"It is a massive blow to confidence in the global economy," said Peter Power, spokesman for the European Commission. "The confidence shot in the arm that we needed badly will not now happen."

After nine consecutive days of talks, discussions reached an impasse when the United States, India and China failed to compromise over measures to protect farmers in developing countries from greater liberalization of trade.

Supporters of the so-called Doha round of talks, which began in 2001, say a deal would have been a bulwark against protectionist sentiments that are likely to spread as economic growth falters in much of the world.

The failure also delivered a blow to the credibility of the World Trade Organization, which sets and enforces the rules of international commerce. It could set back efforts to work out other multilateral agreements, including those intended to reduce the threat of global warming.

The collapse of the talks will not bring an end to world trade, which will continue under current agreements. Many of those agreements are between two or more countries rather than under the WTO.

But it is a big setback, particularly to the hopes of smaller and poorer developing countries, which were counting on gaining greater access to consumers in the United States, Europe and Japan.

Economists and trade experts predicted that negotiators, having come this close, might not find the conditions for a broad deal among the WTO's 153 members for years, if ever again.