UNITED NATIONS, (Reuters) – The United States and  United Nations signed an agreement yesterday clarifying the  world body’s responsibility for coordinating the international  relief efforts in earthquake-ravaged Haiti.

The agreement comes after U.N. officials, aid workers and  diplomats had complained privately about tensions between the  United Nations and U.S. military in the early days after the  Jan. 12 earthquake, as governments scrambled to get urgently  needed aid to the poor Caribbean nation.

“This agreement formalizes the working relationship between  the United States and the United Nations on the ground in  Haiti, and ensures that this cooperation will continue in the  challenging days and weeks ahead,” U.S. ambassador to the  United Nations, Susan Rice, said in a statement.

With an enlarged maximum strength of 12,651 troops and  police, the U.N. peacekeeping mission in Haiti, MINUSTAH, is  responsible for helping Haitian authorities maintain “a secure  and stable environment,” the agreement says.

“The United Nations is coordinating the international  response to the Haitian earthquake,” it says. But it makes clear that the Haitian government has primary  responsibility for the response to the earthquake, security and  in leading the recovery and reconstruction process. The agreement also says the U.S. military, which has over  13,000 military personnel on the ground or offshore in Haiti,  will not don blue helmets but operate under U.S. command. It says the U.S. government commits to supporting relief  work the United Nations says should have priority.     On Wednesday, the French group Doctors without Borders, one  of the world’s top humanitarian aid agencies, accused the  United States of mishandling aid operations in Haiti and  causing severe delays to doctors trying to bring vital help to  victims of the earthquake.    Francoise Saulnier, head of group’s legal department said  days had been lost because the main airport in Port-au-Prince,  now under U.S. control, had been blocked by military traffic. U.N. officials and Western diplomats later played down the  tensions, saying such conflicts were inevitable in the chaos  following a disaster of the scale of the Haitian earthquake.

Edmond Mulet, acting head of the U.N. peacekeeping mission  in Haiti, said on Friday that coordination in delivering aid in  Port-au-Prince and elsewhere had improved and was getting  better every day.