Rohingya militants have set fire to houses in Rakhine state in recent days to intensify the exodus of the Muslim minority, the office of Myanmar's commander-in-chief said Thursday, in an apparent rebuke to fresh accusations of arson by the army.

More than 500,000 Muslim Rohingya have run from communal bloodshed in Myanmar in the last six weeks and numbers are again rising.

This week Bangladesh reported 4-5,000 civilians crossing the border each day after a brief lull in arrivals, with 10,000 more waiting at a frontier area.

Rohingya who have made it to Bangladesh allege the spurt in arrivals follows a redoubled campaign of intimidation and arson by Myanmar's army in parts of Rakhine which were still home to Muslim communities.

But a post on the Facebook page of the office of army chief Min Aung Hlaing said blazes at seven houses in a Rohingya village early Wednesday were started by an "Einu" or a militant from the Arakan Rohingya Salvation Army (ARSA). 

Security forces "working for the rule of law" in Mi Chaung Zay in Buthidaung township helped villagers extinguish the fires which "broke out about 2:40am on October 4th", the post said. 

Accusing "ARSA extremist terrorist" Einu, the statement said he had been "urging people to run" from Rohingya villages to Bangladesh.

The refugee crisis erupted after ARSA raids on Myanmar police posts on August 25.

Refugees who have made it to Bangladesh accuse Myanmar's army -- flanked by mobs of ethnic Rakhine -- of slaughtering them and burning their villages.

Rights groups say satellite data provides evidence of a systematic 'scorched earth' campaign targeting Rohingya villages -- an act the UN says is tantamount to "ethnic cleansing".

But Myanmar's army has denied burning Rohingya villages and consistently accused militants of razing their own homes before fleeing to drum up global support for their cause.

The battery of competing claims is impossible to check independently because the conflict-wracked area of Rakhine is under an army lockdown.

Since the crisis began media and international NGOs have only been given highly controlled access on officially-steered visits.

Myanmar denies the Rohingya citizenship, describing them as "Bengali" interlopers.

It is a well received view inside Myanmar, where the public has shown little sympathy for the Rohingya, lavishing unexpected support on an army that once ruled the country with an iron fist.