Mr Brown is holding talks with Chilean president Michelle Bachelet
Gordon Brown has said people should not be "cynical" about what can be achieved at next week's G20 summit, saying he is optimistic about the likely outcome.
Mr Brown is in Chile on the last leg of a trip designed to build support for joint global economic action in London.
He is holding talks with Chilean president Michelle Bachelet.
Mr Brown says he is optimistic about the summit after Foreign Office minister Lord Malloch Brown said it had to produce more than "empty promises".
Need for action
Lord Malloch Brown, who has been closely involved in preparations for the summit, warned the G20 "can't again engage in meaningless, empty commitments".
Before leaving for Chile, Mr Brown pointed to new US proposals to regulate its banking system as a sign nations were willing to do things inconceivable months ago.
G20 LONDON SUMMIT
World leaders will meet next week in London to discuss measures to tackle the downturn. See
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The G20 countries are Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea, Turkey, the United Kingdom, the US and the EU.
"It is easy to be cynical," he told the BBC "It is easy to say nothing can ever work but we have taken action.
"I haven't been going round the world talking to leaders in every country simply to say we are having a communique. I am going back to say here are the things we are going to do.
"My job is to enable this consensus to be built not just between the US and Brtiain or Europe and US but right round the world in a unique situation."
Huge security will be mounted around the G20 summit amid fears of violent protests against banks and other financial institutions.
Lord Malloch Brown said on Sunday that the financial crisis meant protesters would have "more sympathy" than in past years but stressed they could not be allowed to disrupt the event.
Mr Brown has been under growing pressure at home amid opposition claims of a rift between the government and the Bank of England about the scope for another fiscal stimulus.
You have got to get the debt under control as a key part of restoring confidence because it is confidence that will bring recovery
Conservative leader David Cameron said the prime minister had been "humiliated" by Governor Mervyn King's recent comments that ministers must be "cautious" about plans for further spending given current levels of debt.
"The governor of the Bank of England has been backing up what the Conservative Party has said, which is that you have got to get the debt under control as a key part of restoring confidence because it is confidence that will bring recovery," he said.
"That's the message the prime minister needs to understand."
But Mr Brown said Mr King's comments did not mean he was objecting to any further stimulus measures.
"He didn't say that at all. He said a targeted set of actions maybe necessary. That could include actions on mortgages or climate change or low-carbon recovery or public works and investment."
Mr Brown said ministers could not "rule out" future support for the economy but this could take different forms.
"We have taken very substantial action over the last few months. Obviously we want to look at how that has been effective.
"It is for the chancellor to look at how, in the Budget, he moves the process forward."
Brown: "Things that people could not have thought possible several months ago are now happening"
Mr Brown will hold a series of meetings in Chile, one of the continent's best-performing economies in recent years, as well as attending a meeting of centre-left politicians.
Emerging economies, which are an increasingly powerful voice within the G20, are unhappy the destabilisation of the banking system in the US and Europe has resulted in economic suffering for the world's poorest countries.
During Mr Brown's visit to Brazil, the Brazilian president raised eyebrows when he claimed the financial crisis was caused by "white, blue-eyed people".
At a press conference in Brasilia, President Luiz Inacio Lula da Silva said the crisis clearly originated in the developed world.
"This is a crisis that was caused by people, white with blue eyes," he said. "And before the crisis they looked as if they knew everything about economics."
"Once again the great part of the poor in the world that were still not yet (getting) their share of development that was caused by globalisation, they were the first ones to suffer," he said.
Mr Brown has stressed the need to support developing countries through the economic turmoil, proposing a $100bn fund to underwrite faltering world trade.
Mr Brown has said countries have made great progress through joint action in recent months, spending about $2.5 trillion to boost demand in their economies, and the London summit must build on that progress.
"We have seen over the last few weeks and months how countries have taken action. No we have to bring this together at the G20 meeting in London."
On a whistlestop tour of Europe and the Americas over the past week, the prime minister has addressed the European Parliament, held talks with the UN Secretary General Ban Ki-Moon and met business leaders in New York.
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