All 21 members of the Asia-Pacific Economic Cooperation (Apec) forum have said they would take all necessary measures to respond to the global economic crisis.

In a final declaration issued on Sunday, the leaders vowed to "act quickly and decisively" to combat "one of the most serious economic challenges we have ever faced".

They voiced confidence the world would overcome the financial crisis within 18 months by re-starting global trade talks and resisting protectionism.

In an unusual move, a separate statement on the global economy released on Saturday was modified to voice more optimism.

They said free trade and higher government spending were key to resolving the crisis and supported a big push to revive long-stalled global trade talks by seeking agreements on contentious farming and manufactured goods.
   
The Apec leaders' declaration at the end of a two-day summit in the Peruvian capital Lima, echoed the measures called for by the "Group of 20" major economies at a meeting in Washington a week earlier, but widened the level of support for drastic action to stimulate lending and spending.

Lucia Newman, Al Jazeera's correspondent in Lima, said: "In concrete terms they made a very strong commitment to keep markets open and to denounce any governments that would attempt to impose protectionist measures ... and finally a commitment to really step on the gas to finalise the Doha round of free trade talks.

Optimism

George Bush, the US president, strongly defended his free trade ideology at the summit.

While he received praise from Hu Jintao, the Chinese president, and Taro Aso, the Japanese prime minister, Bush had a more tense final exchange with Dmitry Medvedev, the Russian president, on the sidelines of the Apec meeting.

The two reportedly discussed the conflict between Russia and Georgia over South Ossetia and Moscow's opposition to US plans to base a missile defence system in Eastern Europe.

In another high-profile meeting, Bush, Aso and Lee Myung-Bak, the South Korean president, met to jointly press North Korea over a stalled six-nation pact on ending its nuclear programme.

The three leaders called on Pyongyang to draft a document showing how it will carry out a landmark disarmament-for-aid deal.

The Apec gathering of 21 countries account for nearly half of the world's trade.