WASHINGTON, April 14 (Xinhua) -- The United States on Friday warned Chad not to carry out its threats to expel some 200,000 Sudanese refugees in retaliation for Khartoum's alleged backing ofa Chadian rebel offensive.

    State Department spokesman Sean McCormack issued the warning after Chadian President Idriss Deby announced that his country haddecided to cut off diplomatic ties with neighboring Sudan, and threatened to expel some 200,000 Sudanese refugees if no solution was found to the Darfur crisis by the end of June.

    "We are ... working to confirm with the government of Chad exactly what their stance is on this and to underline in the strongest possible terms that such an action would be unacceptable," McCormack said.

    "We call upon the government of Chad to uphold its responsibilities, as outlined by the UN, and international obligations to provide protection for these refugees as well as toprovide international access to the refugees," he added.

    McCormack said Washington was unable to confirm whether Khartoum was involved in Chad, but added that the U.S. government would find any proof of a Sudanese role "very disturbing."

    "Very clearly, any sort of assistance to an armed incursion is unacceptable behavior," he said. "It's unacceptable behavior for aneighbor to act in such a way."

    It was reported that rebels marching toward N'Djamena, the capital of Chad, battled with government forces on Thursday, leaving hundreds of people dead.

    Sudan denied any involvement in the fight. Enditem