At a press conference in Pittsburgh, where the Prime Minister is attending the G20 meeting of world leaders, Kevin Rudd said watching the trade talks had been like watching grass grow or paint dry.

While there was the political will to conclude the round, there was still a challenge to achieve an outcome.

"There are still areas of technical disagreement. Our challenge is to fix them and to achieve, across our numbers, the political will to put the ball over the try line," he said.

"Australia strongly supports the earliest possible conclusion of the Doha round.

"We need to find large new sources of economic growth. One of those areas for growth is to conclude the round.

"The Peterson Institute in Washington's done their study: there's nearly $1 trillion worth of additional activity in the global economy if we free up markets - great for developing countries, great for developed countries, great for the global economy at a time when it actually needs a shot in the arm.

"But I don't want to create the impression that this will mysteriously pop out tomorrow afternoon at five past five."

The Prime Minister returns home to Australia this weekend.