Police trucks in Sittwe, Rakhine State, Monday. Pic: AP.

YANGON, Burma (AP) — The United States is calling on Burma to lift travel restrictions on humanitarian workers trying to get to Rakhine state, where tens of thousands of Muslims are living in displacement camps.

Hundreds of aid workers fled the state last week after extremist Buddhist mobs attacked their residences and offices, accusing them of favoring Muslims. Several aid agencies sought to return but were denied permission.

(MORE: Full extent of anti-NGO attacks in western Burma emerging)

The U.S. called on the government to facilitate the appropriate travel authorizations to the United Nations and other humanitarian organizations so they could get back to work.

Aid groups say clean water and food stocks are starting to run out. Emergency medical referrals are at a near standstill.

In the past two years, up to 280 people have been killed, most of them Rohingya Muslims.