The U.N. Security Council is urging Myanmar's government to allow international investigators to help probe allegations of human rights violations against Rohingya Muslims, saying it remains "gravely concerned" at their plight.

In a letter to Myanmar's leaders obtained Tuesday by The Associated Press, the council noted the government's commitment to investigate all allegations of violence.

It said independent and transparent investigations "with involvement of the international community ... would turn this commitment into concrete action and ensure that all perpetrators of human rights violations and abuses are held to account."

The council also urged Myanmar's government to grant U.N. agencies and humanitarian organizations immediate access to Rakhine state.

Rohingya insurgent attacks last August were followed by a military crackdown that led some 700,000 Rohingya to flee to Bangladesh.