Barack Obama has hailed the “historic” agreement at today’s London G20 summit that will see $1 trillion worth of resources deployed to combat the global recession.

The United States president was the last world leader to address journalists as the two-day summit closed at ExCel in east London.

In front of a packed briefing room President Obama said a “turning point” in leaders’ pursuit of recovery had been reached.

“The London summit is historic – due to the challenges we face and magnitude of our response,” he said.

“So many have lost so much and we owe it to all of our citizens to act and act with urgency. The whole world has been touched by this devastating downturn.”

Earlier on Thursday Gordon Brown had announced a package of measures designed to drag the world’s leading and developing economies out of the downturn. International financial institution reform and crackdowns on tax-havens and protectionist economies were also unveiled.

President Obama said he was “very proud” of Mr Brown.

But he added that the newfound “era of responsibility… cannot end at our borders”.

“What we have announced is not a panacea but a critical step.

“We have a patient… we gave it some medicine which stabilised it. It is still suffering from many wounds.”