Bangladesh has told the UN it cannot accept any more refugees from Myanmar, the first time the country has threatened to close its borders to Rohingya fleeing violence.

Bangladesh is now sheltering more than a million Myanmar refugees in camps, some 700,000 of whom have poured over the border in the past 18 months having fled a military-led crackdown in Rakhine state where thousands were killed, women were raped and villages razed.

Speaking to the UN security council on Thursday, Bangladesh foreign secretary Shahidul Haque said: “I regret to inform the council that Bangladesh would no longer be in a position to accommodate more people from Myanmar.”

Most of the Rohingya arrived in Bangladesh between August and December 2017 in the midst of the brutal campaign of violence the UN has described as ethnic cleansing and possible genocide. However, last year about 16,000 Rohingya crossed the border to Bangladesh, fleeing ongoing abuses. A UN envoy stated last year there was still an “ongoing genocide” in Rakhine.

Nonetheless, this year arrivals have slowed, with organisations reporting some weeks with no refugees crossing the border.

Bangladesh was lauded for its willingness to keep its borders open and welcome the hundreds of thousands of refugees with open arms. However Haque said the situation in Cox’s Bazar – where the millions of mainly Rohingya refugees are living in what has become the world’s largest refugee camp – was now untenable and had gone from “bad to worse”.

“Is Bangladesh paying the price for being responsive and responsible in showing empathy to a persecuted minority population of a neighbouring country?” Haque said.

In particular Haque expressed his frustration with both the UN security council and the international community at the lack of concrete action to solve the crisis. He accused Myanmar of trying to shift the blame by accusing Bangladesh of harbouring terrorists when in fact the Bangladesh government had “a zero-tolerance policy” in this regard.

Haque was joined in his condemnation of Myanmar’s failure to take steps towards repatriation of Rohingya by envoys from western governments including the UK and the US. “We are very disappointed that there hasn’t been more progress on getting the refugees back,” said British ambassador Karen Pierce.

Initial attempts to begin a repatriation process for the Rohingya last year failed spectacularly after Myanmar failed to provide assurances to the refugees that they would be safe from violence, be allowed to return to their original homes, have freedom of movement and be given a pathway to citizenship in Myanmar, which Rohingya were stripped of in 1974. As a result, the thousands of Rohingya listed for return refused, and many went into hiding.

As Haque pointed out to the UN security council, “not a single Rohingya has volunteered to return to Rakhine due to the absence of a conducive environment there”.

However, Myanmar’s ambassador, Hau Do Suan, was on the defensive, emphasising that there were “huge physical as well as psychological barriers” to overcome before repatriation could begun.

“We are confident that we can make the repatriation plan a success if we both act strictly in compliance with the agreements,” he said.