The United States has condemned the Sudanese government for bombing rebel positions in the troubled Darfur region in violation of a ceasefire agreement.

A State Department spokesman, Sean McCormack, says government warplanes bombed areas around Um Rai in northern Darfur over the past week. He says the bombings began immediately after a meeting between rebels and representatives of the African Union and the United Nations.

The spokesman says the United States is also deeply concerned by rebel attacks on humanitarian workers in the southern Darfur area of Gereida.

The latest violence comes as the African Union and the United Nations ready for a series of talks on Darfur next week. The U.N. special representative for Darfur, Jan Eliasson, says the objective is to reduce violence through the political process.

The United Nations is also seeking to deploy U.N. troops to Darfur to support a struggling African Union force. Sudan's president, Omar al-Bashir, agreed to the joint AU-U.N. force last month after many months of refusing to allow any U.N. troops into Darfur.

Meanwhile, the United States says President Bush's special envoy to Sudan, Andrew Natsios, will travel to China Monday to encourage officials there to exercise their influence on Sudan to help bring about peace in Darfur.

Some information for this report was provided by AFP, AP and Reuters.