Nairobi/Abuja, July 30 (DPA) Nigerian Islamists have fled an army onslaught after four days of fighting that killed over 200 people, media reports said Thursday.

Boko Haram, a group called the Nigerian Taliban, launched a series of attacks on police stations across northern Nigeria Sunday.

The military has since struck back, killing and arresting hundreds.

Troops Wednesday laid siege to the compound of Mohammed Yusuf, the group's leader, in the town of Maiduguri, Borno state.

According to the Nigerian military, the militants have now fled the city with the army hot on their heels, the BBC reported.

Nigeria, Africa's most populous nation with around 150 million inhabitants, is split between the Muslim north and the Christian and animist south.

Boko Haram, which was formed in 2002, wants to impose sharia, or Islamic law, across the whole of Nigeria and is also opposed to Western education.

The group launched its first attack on a police station in Bauchi, sending around 70 men armed with automatic weapons and grenades into the fray.

The police repelled the initial attack, killing dozens of militants, but the violence then spread.