But the diplomats failed to condemn atrocities committed by the country's security forces and vigilante Buddhist mobs against the Rohingya Muslim ethnic minority there.

The United Nations has described the violence as ethnic cleansing and Human Rights Watch said it amounts to crimes against humanity.

Foreign Minister Julie Bishop said two weeks ago she does not blame Myanmar's government led by Aung Sun Suu Kyi for the atrocities that sparked a mass exodus of more than 500,000 Rohingya Muslims from Rakhine since late August, saying the Nobel laureate must be part of a solution.

The exodus is the largest movement of a civilian population in Asia in decades and has created an emergency in squalid refugee camps just over the border in Bangladesh.

In a statement after the one-day government-sponsored tour on Monday, Mr Coppel and the other diplomats called on Myanmar authorities to fully investigate allegations of human rights violations and allow unimpeded humanitarian access to Rakhine.

"We saw villages that had been burnt to the ground and emptied of inhabitants," the statement said.

"The violence must stop. The security forces have an obligation to protect all people in Rakhine without discrimination and to take measures to prevent acts of arson," it said.

The diplomats condemned an insurgent group called the Arakan Rohingya Salvation Army (ARSA) which attacked 30 police posts and a military base on August 25.

The attacks prompted a brutal military offensive during which villages were torched and hundreds of mostly Rohingya were killed.

Survivors have described rapes and indiscriminate shooting of Rohingya trying to flee.

The statement expressed "our deep concern about violence and mass displacement" of people in the state.

It also called on Myanmar's government to allow UN investigators to enter Rakhine, home to 1.1 million Rohingya for generations.

"We saw on our visit the dire humanitarian need," the ambassadors said.

"We call once more for unimpeded access to northern Rakhine and resumption of life-saving services without discrimination in the state."

Convoys delivering desperately needed food and other essentials stopped deliveries across Rakhine in late August when Ms Suu Kyi linked international aid agencies with the insurgents, who she called terrorists. Agency staff were afraid to return to work for their safety.

Myanmar has told the UN refugee agency its priority is to bring back Rohingya who have fled to Bangladesh.

But Win Myat Aye, Myanmar's Minister for Relief and Resettlement said that although the security situation has improved in Rakhine "much needs to be done to consolidate stability in the region".

Despite rising tensions over the crisis, Bangladesh and Myanmar have agreed to set up a working group to plan the repatriation of the refugees to Rakhine.

But it remains unclear who Myanmar will approve to return through what it calls a "verification process".

Rohingya are denied citizenship and other basic rights and are classified as illegal immigrants in Rakhine. Many of the Rohingya in the Bangladesh camps have no identification papers.

Karim Elguindi of the UN World Food Program who is in charge of delivering food to the camps, described the situation in them as distressing and warned more Rohingya are on the way.

- with agencies