SUDAN said yesterday it was doing all it could to stem violence in Darfur as the United States deputy secretary of state, Robert Zoellick, visited Khartoum to pile on pressure backed by huge aid pledges.

Mr Zoellick is on a two-day visit to Africa’s largest country to keep up pressure on Sudan to implement a north-south peace deal and end killings in Darfur.

Sudan’s first vice-president, Ali Osman Mohamed Taha, said: "We are working diligently to stop the violence; not only to stop the violence but to resolve the conflict through political negotiations and get Darfur back to normalcy."

Mr Taha has made similar statements in the past but reports from regional aid workers say Sudan has failed to deliver.

Donors exceeded Sudan’s aid requests this week by pledging £2.4 billion at an international conference in Oslo to help the south recover from Africa’s longest civil war.

Tens of thousands of people have been killed in the fighting in Darfur and more than two million have fled their homes to makeshift camps in the remote, western desert region.

The United Nations Human Rights Commission was last night set to vote on a resolution condemning the violence in Darfur.

African countries such as Libya, Zimbabwe and Sudan itself may put forward a "no-action" motion, said Loubna Freih, Geneva director of Human Rights Watch.

"We hope that the commission will finally take a proper step in the right direction in acknowledging the violations committed by the government of Sudan and its militias in Darfur," Ms Freih said.

Last year, the commission stopped short of formal condemnation of Sudan