The number of Rohingya refugees who have fled to Bangladesh since violence broke out in Myanmar's Rakhine state on August 25 has exceeded half a million, the United Nations said Thursday.

The new figure of 501,800 -- up from around 480,000 -- was due mainly to the counting of refugees not previously included in the tally rather than a dramatic increase in arrivals.

The refugees are fleeing a fresh security operation in which security forces and Buddhist mobs have killed men, women and children, looted homes and torched Rohingya villages. According to Bangladeshi Foreign Minister Abul Hasan Mahmood Ali, around 3,000 Rohingya have been killed in the crackdown.

Turkey has been at the forefront of providing aid to Rohingya refugees and President Recep Tayyip Erdogan raised the issue at the UN.

The Rohingya, described by the UN as the world's most persecuted people, have faced heightened fears of attack since dozens were killed in communal violence in 2012.