GENEVA: Amid mounting reports of violent unrest and brutal reprisals by Myanmar’s army in the mainly Muslim state of Rakhine, a United Nations expert said that the country’s government should let aid agencies into the area and investigate allegations of abuse instead of brushing them aside with blanket denials.

Last month, after insurgents attacked border posts, killing nine police officers, the authorities in Myanmar closed the south western state to aid agencies and independent journalists. The army sent in more troops and helicopter gun ships in the past week after further attacks resulted in military casualties.

The security lockdown was “not acceptable,” said the United Nations expert monitoring events in Myanmar, Yanghee Lee. In a statement, Ms. Lee drew attention to unverified reports that the military had carried out the summary execution, torture and rape of Rohingya Muslims, as well as the destruction of mosques and houses.

A closely supervised two-day visit to the region arranged by the authorities for 10 diplomats in early November did little to address the humanitarian crisis and should not be used as a “smoke screen” for giving the military a free hand to increase its operations, Ms. Lee said.

Samantha Power, the United States’ ambassador to the United Nations, wrote on Twitter that the Security Council discussed the violence in Rakhine State on Thursday night and called for the resumption of humanitarian aid for the region and an international investigation into the accusations of abuses by the military.

International aid agencies say they have heard reports that hundreds of Rohingya Muslims have crossed into Bangladesh to escape the crackdown and that others were shot dead as they headed for the border.

Ms. Lee also expressed skepticism over a statement by Ms. Aung San Suu Kyi that the government’s response to the violence in Rakhine State was based on the rule of law, echoing growing unease that she is doing little to rein in Myanmar’s powerful military establishment.

“I am unaware of any efforts on the part of the government to look into the allegations of human rights violations,” Ms. Lee said. “It would appear, on the contrary, that the government has mostly responded with a blanket denial.”