Yangon: Muslim militants in Myanmar staged a coordinated attack on 30 police posts and an army base in Rakhine state on Friday, and at least 59 of the insurgents and 12 members of the security forces were killed, the army and government said.

The fighting marked a major escalation in a simmering conflict in the north-western state since last October, when similar attacks prompted a big military sweep beset by allegations of serious human rights abuses.

Former UN secretary-general Kofi Annan: "No cause can justify such senseless killing." Credit:AP

The Arakan Rohingya Salvation Army (ARSA), a group previously known as Harakah al-Yaqin, which instigated the October attacks, claimed responsibility for the early morning offensive, and warned of more.

The treatment of approximately 1.1 million Muslim Rohingya has emerged as majority Buddhist Myanmar's most contentious human rights issue as it makes a transition from decades of harsh military rule.