A report by United Nations investigators saying Myanmar's military carried out mass killings and gang rapes of Muslim Rohingya with "genocidal intent," and that the country's commander-in-chief and five generals should be prosecuted, deserves serious consideration, the UN secretary-general has said.

Antonio Guterres told a meeting of the UN Security Council, the day after the report was published, that accountability was essential for genuine reconciliation between all ethnic groups.

Without using the word genocide, Mr Guterres said the report by independent experts found "patterns of gross human rights violations and abuses" committed by the security forces, which it said "undoubtedly amount to the gravest crimes under international law."

"I believe this report's findings and recommendations deserve serious consideration by all relevant United Nations bodies," Mr Guterres said.

He said international cooperation would "be critical to ensuring that accountability mechanisms are credible, transparent, impartial, independent and comply with Myanmar’s obligations under international law."

Mr Guterres said the UN Security Council needed to continue to press for the release of journalists arrested for reporting on the Rohingya crisis, a reference to two Reuters reporters on trial in Myanmar.

Some 700,000 Rohingya have fled the crackdown in Myanmar and most are living in refugee camps in neighboring Bangladesh.

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Mr Guterres said an international humanitarian appeal for the crisis remained significantly underfunded at 33% and more must be done to alleviate the threats to life from the current and impending monsoons.

He said it was clear that conditions do not yet exist for the safe return of Rohingya refugees to their place of origin or choice and called on Security Council members to join him in urging Myanmar to cooperate to ensure access to UN agencies and partners.

"There can be no excuse for delaying the search for dignified solutions that will allow people to return to their areas of origin in safety and dignity, in line with international standards and human rights," Mr Guterres said.

A spokesman for the US State Department, which is preparing its own report on the anti-Rohingya campaign, said yesterday that the UN findings added to growing evidence of "widespread human rights abuses" by Myanmar forces.

However, the United States would only decide whether genocide or crimes against humanity had been committed "after a thorough review of the available facts and relevant legal analysis," the spokesman said.

Critics have accused Washington of an overly cautious response to the Rohingya crisis, but a US official said the UN findings could increase pressure for tougher US action.