PRESS ASSOCIATION -- Prime Minister David Cameron has warned that failure to act swiftly over eurozone indebtedness would "lengthen the shadows of uncertainty" looming over the global economy.

In a speech before the Canadian parliament, the premier called on indebted nations to make tough decisions in order to repair their broken balance sheets.

Surplus economies had a role to play too by stimulating demand, and refocusing spending to help deficit countries increase their exports, Mr Cameron suggested.

In Ottawa following a two-day visit to New York, Mr Cameron pressed home the need for quick action to avert the eurozone crisis deepening.

Speaking at the end of a day which saw global markets tank, Mr Cameron called on European nations to show they had the "political will" to "do what is necessary".

He continued: "One way or another, they have to find a fundamental and lasting solution to the heart of the problem - the high level of indebtedness in many euro countries."

High oil and food prices, the Japanese earthquake and stagnating growth in Europe and the US had hampered economic recovery, the PM added. "We are not quite staring down the barrel, but the pattern is clear, the recovery out of the recession for the advanced economies will be difficult," Mr Cameron said.

Reiterating his opposition to Britain ever joining the euro, Mr Cameron said experience had shown that "different countries sometimes need very different economic policies".

But a global response was needed because the size of eurozone problems are now "so big that they have begun to threaten the stability of the world economy," the Prime Minister added.

Mr Cameron has put his name to a letter to G20 president France - also signed by the leaders of Australia, Canada, Indonesia, Mexico and South Korea - warning that the path out of recession will be "difficult" and arguing that the world's biggest economies must agree at the Cannes Summit in November to work together to increase global demand without creating unsustainable imbalances.