The United Nations Security Council renewed the mandate for peacekeepers in Darfur on Thursday in a resolution that the United States criticised for raising concerns about moves to indict Sudan's president for genocide.
Most Western powers accepted wording that makes clear the council would be willing to discuss freezing any International Criminal Court indictment of President Omar Hassan al-Bashir for genocide in the interest of peace in Darfur.
Of the 15 council members, 14 voted for the resolution. The US rejected the section on the ICC and abstained.
Five years of war have brought humanitarian disaster to the western Sudanese region, and Darfur campaigners accuse the world of failing to provide helicopters and other badly needed support for the struggling peacekeeping mission there.
The US backed the basic point of the resolution to extend the mission until the end of July 2009, but criticised a key paragraph in the British-drafted text added to accommodate African concerns about the ICC.
"The United States abstained from the vote because language added to the resolution would send the wrong signal to Sudanese President Bashir and undermine efforts to bring him and others to justice," said US Deputy Ambassador Alejandro Wolff, who repeatedly referred to the "genocide" in Darfur.
The US delegation did not veto the resolution, which would have left the peacekeeping mission in a legal vacuum. However, council members had wanted a unanimous vote to show undivided support for peacekeepers in the line of fire in Darfur.
Human Rights Watch welcomed the US abstention, saying it was a vote against "get out of jail free card" for Mr Bashir.
Britain's UN ambassador John Sawers, who led negotiations on the resolution, said he regretted the lack of unanimity. He also criticised linking the ICC to the troops' mandate.
The vote was postponed several times as council members tried to persuade the Americans to vote yes. The vote took place hours before the mandate for UNAMID - the joint UN-African Union peacekeeping force - was to expire.
International experts and UN officials estimate at last 200,000 people have died and 2.5 million been driven from their homes in Darfur since mostly non-Arab rebels took up arms in early 2003 accusing central government of neglect. Khartoum says 10,000 people have been killed.