A gunbattle between security forces and Islamic militants fighting to create a Taliban-style state in northern Nigeria (search) left 29 people dead, most of them militants, police said Friday.

In the southern oil region, meanwhile, clashes between troops and tribal militia fighters forced oil giant Royal Dutch/Shell to evacuate two facilities, the company said Friday. However, Shell said there was no disruption to its production and exports.

Security forces have been battling militants in the north this week after Islamic fundamentalist gunmen launched their first attack since January, assaulting police stations in two towns — Bama and Gworza — and killing four police officers and two civilians on Monday.

Since then police and army troops have pursued the militants and on Thursday engaged in a gunbattle in the Gworza hills, near the border with Cameroon, killing 27 militants and two police, said Ade Ajakaiye, police commissioner for Borno state.

Security forces recovered 22 assault rifles and large quantities of ammunition in the operation. Five militants who fled across the border into Cameroon were arrested by authorities there and will be returned to Nigeria, Ajakaiye told the AP.

Nigerian army spokesman Col. Mohammed Yusuf confirmed that troops of the army's 21st Armored Brigade were involved with police in the operation to flush out the militants.

"We will get rid of them whether they're in the hills or the valleys," Yusuf said.

The radical sect known as Al-Sunna wal Jamma (search) comprises mainly university students seeking to create a Taliban-style state in Africa's most populous nation.

It launched its first wave of attacks Dec. 31, targeting several police stations in northeastern Yobe state. Its uprising was put down by a government offensive in January that killed 20 militants and led to the arrests of 40 more.

Although the group lacks popular support, it was the first armed push for a strict Islamic regime in Nigeria's predominantly Muslim north since 12 states in the region — including Yobe and Borno — began adopting the Islamic Shariah legal code in 2000.

Nigeria, a nation of more than 126 million people, is made up of a majority-Muslim north and a heavily Christian south and is frequently rocked by sectarian violence.

In the south, the military was launching an offensive against militia fighters around Sombreiro River, said Army spokesman Capt. Ogbonna Kanu.

Shell evacuated the Soku gas platform and the Ekulama oil pumping station as a "precautionary safety measure" because of clashes nearby, a company spokesman said. Shell accounts for about half of Nigeria's daily exports of 2.5 million barrels.

In pre-dawn fighting on Friday, militia fighters pushed back government troops along the river, said militia leader Moujahid Dokubo-Asari (search).

"They were forced to withdraw. We also withdrew because daylight was approaching and we wanted to avoid raids by helicopter gunships," Dokubo-Asari told The Associated Press by satellite phone.

Dokubo-Asari said his fighters suffered no casualties, but he could not say whether any soldiers were killed.

Dokubo-Asari's Niger Delta People's Volunteer Force (search) claims to be fighting for self-determination for an estimated 8 million ethnic Ijaws, the largest tribe in the impoverished oil region. Locals there accuse joint ventures run by the government and oil companies of cheating them out of wealth produced in their land.