International donors have pledged 4.5 billion US dollars to help rebuild Sudan while the United States warned that the aid is dependent on the situation in Sudan's Darfur region, reports from Oslo, Norway, said Tuesday.

"This conference has pledged 4.5 billion dollars for 2005, 2006 and 2007," Norway's Minister for Development Aid Hilde Frafjord Johnson said at the closing of the donors' conference held in the Norwegian capital.

She said the pledges had exceeded the requested 3.6 billion dollars. The United Nations had sought 1 billion dollars for Sudan in 2005 while the African country itself had requested 2.6 billion dollars for the 2005-2007 period.

Conflicts erupted in Sudan's troubled western region of Darfur in February 2003 after the Sudan Liberation Army and the Movement of Equality and Justice took up arms against the government.

A peace accord signed in January ended the 21-year civil war in southern Sudan, but violence continues unabated in a separate conflict in Darfur.

The conflicts have left tens of thousands of people dead and many others displaced and now aid is needed to relieve hunger, help refugees and build infrastructure.

John Garang, head of southern Sudan's former rebels, said he was satisfied with the pledges made at Tuesday's conference.

However, Johnson, the Norwegian minister who chaired the conference, cautioned that collecting the exact amounts promised from donors could be difficult.

The United States, a major donor which has promised to provide between 1 and 2 billion dollars in aid over the next two years, has conditioned financial support to Sudan's north-south peace deal on resolving the conflict in Darfur region, US Deputy Secretary of State Robert Zoellick said.