ABUJA (Reuters) - The United States said on Wednesday reports suggested Nigerian President Umaru Yar'Adua may be too ill to resume office and said it hoped his return was not a bid by those around him to trigger renewed uncertainty.

"We hope that President Yar'Adua's return to Nigeria is not an effort by his senior advisers to upset Nigeria's stability and create renewed uncertainty in the democratic process," U.S. Assistant Secretary of State Johnnie Carson said in a statement released by the U.S. embassy in Nigeria.

(Reporting by Nick Tattersall)