YANGON (AFP) - Rohingya militants, whose Aug 25 raids in Myanmar's Rakhine State sparked an army crackdown that has seen nearly 300,000 of the Muslim minority flee to Bangladesh, on Sunday (Sept 10) declared a unilateral one-month ceasefire.

"The Arakan Rohingya Salvation Army (Arsa) hereby declares a temporary cessation of offensive military operations," it said in a statement on its Twitter handle @Arsa-Official, adding it was to allow for humanitarian aid to reach the battered region.

The group urged "all humanitarian actors" to resume aid delivery to "all victims of humanitarian crisis irrespective of ethnic or religious background" during the ceasefire period which runs until Oct 9.

It urged Myanmar to "reciprocate this humanitarian pause" in fighting, with huge numbers of displaced moving across Rakhine many believed to be in desperate need of help after over two weeks of violence.

Its Twitter page is often the first to publish Arsa statements or direct readers to videos.

Sunday's statement was signed by Ata Ullah, who purportedly commands the militants from jungle bases straddling the Bangladesh-Myanmar border.

Better-known locally as Harakah al-Yaqin (Faith Movement), Arsa launched coordinated raids using hundreds of militants on Aug 25 on around 30 police posts and state offices in northern Rakhine state.

The kickback by security forces prompted the Rohingya exodus.

Rohingya refugees in Bangladesh say security forces and ethnic Rakhine Buddhists killed villagers indiscriminately during their crackdown, setting fire to hundreds of villages.

In an area split by claim and counterclaim, ethnic Rakhine villagers accuse militants of murdering their civilians while the government says fleeing Rohingya set fire to their own homes to forment fear and anti-state anger.

Arsa appears to have significantly grown in the last year despite remaining hopelessly outgunned against one of Asia's largest militaries.

According to statements and photos released by Myanmar's army, the militants use primitive weapons, including gunpowder rifles, homemade guns and bombs as well as clubs and swords.

Myanmar's army says it has killed nearly 400 militants so far in its "clearance operations", while some Rohingya refugees have complained they were forced to fight by Arsa.