Myanmar on Sunday rebuffed a ceasefire declared by Muslim Rohingya insurgents to enable the delivery of aid to thousands of displaced people in the violence-racked state of Rakhine, declaring simply that it did not negotiate with terrorists.

Attacks by militants on police posts and an army base on Aug. 25 prompted a military counter-offensive that triggered an exodus of Rohingya to Bangladesh, adding to the hundreds of thousands already there from previous spasms of conflict.

According to the latest estimate by U.N. workers in the Cox’s Bazar region of southern Bangladesh, about 294,000—many of them sick or wounded—have arrived in just 15 days, putting huge strain on humanitarian agencies’ operations.

Thousands of Rohingya remaining in the north-western state of Rakhine have been left without shelter or food, and many are still trying to cross mountains, dense bush and rice fields to reach Bangladesh.

The Arakan Rohingya Salvation Army (ARSA) insurgent group declared a month-long unilateral ceasefire, starting on Sunday, so that aid could reach these people.

The impact of ARSA’s move is unclear, but it does not appear to have been able to put up significant resistance against the military force unleashed in Rakhine state, where thousands of homes have been burned down and dozens of villages destroyed.

ARSA’s declaration drew no formal response from the military or the government of Buddhist-majority Myanmar. However, the spokesman for Myanmar’s leader, Aung San Suu Kyi, said on Twitter: ‘We have no policy to negotiate with terrorists.’

Myanmar says its security forces are carrying out clearance operations to defend against ARSA, which the government has declared a terrorist organisation.

Human rights monitors and fleeing Rohingya say the army and Rakhine Buddhist vigilantes have mounted a campaign of arson aimed at driving out the Rohingya, whose population is estimated at around 1.1 million.

About a dozen Muslim villages were burned down on Friday and Saturday in the ethnically mixed Rathedaung region of Rakhine, two sources monitoring the situation said.

‘Slowly, one after another, villages are being burnt down—I believe that Rohingyas are already wiped out completely from Rathedaung,’ said one of the sources, Chris Lewa of the Arakan Project, a Rohingya monitoring group.

It was unclear who torched the villages, and independent journalists are not allowed into the area.