"President Saleh has publicly expressed his willingness to engage in a peaceful transfer of power; the timing and form of this transition should be identified through dialogue and begin immediately," State Department spokesman Mark Toner said in a statement.

The spokesman also called for "genuine participation" from all sides and urged them to refrain from violence.

His comments came after a senior official for Yemen's ruling General People's Congress said the party has accepted a plan from the six-nation Gulf Cooperation Council under which Saleh would stand down.

Gulf Arab nations have also proposed forming a government of national unity in Yemen, Saleh transferring his powers to his vice president and an end to deadly protests rocking the impoverished country.

"We will not speculate about the choices the Yemeni people will make or the results of their political dialogue. It is ultimately for the people of Yemen to decide how their country is governed."