Prime Minister Gordon Brown has said the "whole world should be committed" to overcoming the economic downturn and tackling protectionism "head-on".
He reiterated his calls for countries to work together in response to global recession, saying trade would help "the poorest and most vulnerable".
There had to be "fundamental reform" of financial regulation, Mr Brown added.
The prime minister was speaking after Downing Street talks with EU Commission president Jose Manuel Barroso.
Mr Brown's comments come after a meeting of European finance ministers in Horsham, West Sussex, at the weekend, and ahead of the summit of G20 leaders in London on 2 April.
'Help the poorest'
At a Downing Street press conference he said: "We are seeing a large fall in world trade...
"The 1930s brought protectionism in response to recession; in 2009 we must tackle protectionism head-on."
The prime minister said any package must "help the poorest, who are in the end the most hard hit by the global recession".
He added: "The G20 must have a focus on the poorest and most vulnerable... We need fundamental reform of the international regulatory system."
Mr Brown said: "I think the whole world should be committed to the sustained effort that is needed to sustain growth."
Mr Brown also endorsed Mr Barroso for another term as Commission president.
Mr Barroso said: "This recession is affecting every European household...
"Profits cannot be private while debts are public. We need ethics back in the financial system.This article is from the BBC News website. © British Broadcasting Corporation