The United States harshly criticized Myanmar Thursday over the ethnic cleansing of minority Rohingya Muslims, saying the bloodshed in Rakhine state had shamed Aung Sang Suu Kyi's government.

Speaking at a United Nations Security Council meeting, U.S. Ambassador Nikki Haley pressed for members of Myanmar's military to face action from the global body in response to the violence and expressed sharp criticism of the civilian government.

"We cannot be afraid to call the actions of the Burmese authorities what they appear to be: a brutal, sustained campaign to cleanse the country of an ethnic minority," said Haley, using an alternative name for Myanmar.

"And it should shame senior Burmese leaders who have sacrificed so much for an open, democratic Burma," she added.

Haley also urged all countries to suspend arms sales to Myanmar and the prosecution of military members involved in the bloodshed.

"The time for well-meaning, diplomatic words in this council has passed. We must now consider action against Burmese security forces who are implicated in abuses and stoking hatred among their fellow citizens."

More than 500,000 Rohingya have fled to Bangladesh since August, U.N. Secretary-General Antonio Guterres said Thursday.

Speaking to reporters earlier in the day, U.N. deputy spokesman Farhan Haq called it "the largest mass refugee movement in the region in decades".

Since Aug. 25, approximately 480,000 Rohingya have crossed from Myanmar's western state of Rakhine into Bangladesh, according to the U.N.

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 Erdoğan has said he will raise the issue at the U.N.

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

Last October, following attacks on border posts in Rakhine's Maungdaw district, security forces launched a five-month crackdown in which, according to Rohingya groups, around 400 people were killed.

The U.N. documented mass gang rapes, killings -- including of infants and young children -- brutal beatings, and disappearances committed by security personnel. In a report, U.N. investigators said such violations may have constituted crimes against humanity.