Harare - Zimbabwean Prime Minister Morgan Tsvangirai left Harare Saturday for a three-week-long trip that will include meetings with US President Barack Obama and British Prime Minister Gordon Brown, in an effort to raise funds to aid his country's struggling economy.

"In the US I'm meeting president Barack Obama. I'm optimistic because Zimbabwe has gone through a very difficult period and its time that we put (our) case across," said the 57-year-old former opposition leader at Harare airport before his departure.

Tsvangirai said that the trip was also aimed at ending the "international isolation" of Zimbabwe.

Zimbabwe's economy, devastated by years of political strife under President Robert Mugabe, is in need of billions of dollars in investment and aid.

A unity government including the former political rivals Tsvangirai and Mugabe was formed in February. Mugabe is officially banned from visiting Europe or the US.

"The country needs transitional finances in a number of areas for recovery. I hope that we will be able to put our case for the rest of the world to give the inclusive government the benefit of the doubt," Tsvangirai said.

As well as Obama and Brown, Tsvangirai is scheduled to meet French President Nicolas Sarkozy, German Chancellor Angela Merkel as well as the leaders of Sweden, Norway, Denmark, Belgium and senior European Union officials.

The US, the EU and other Western donors want to see evidence of substantial reforms before providing any development aid. Despite some progress in curbing inflation and easing food shortages, the government has been paralysed by disagreements between the parties.

Finance Minister Tendai Biti says Zimbabwe needs over 8 billion dollars to turn around the economy. So far, however, Harare has raised only 1 billion dollars in credit lines from mainly African countries and institutions. (dpa)