Four visiting U.S. lawmakers called during a visit to Nigeria on Sunday for a special fund for victims of the Boko Haram insurgency that has claimed thousands of lives and seen the abduction of dozens of schoolgirls.

"Today we call upon the government of Nigeria to establish a national victim fund for all the victims who are suffering at the hands of Boko Haram," delegation co-chair Sheila Jackson Lee told reporters in the capital Abuja.

Supporters of the more than 200 schoolgirls abducted by Boko Haram Islamists two months ago vowed Saturday to scale up the pressure on the Nigerian government to rescue them.

Noisy street demonstrations in Abuja and other cities have become a regular feature of the campaign to keep the issue in the public eye two months after the girls were abducted from a school in the remote northeastern town of Chibok on April 14.

Nigeria's main opposition party has taken up the issue of insecurity, slamming President Goodluck Jonathan's party for failing to stem the rising violence, ahead of what it calls "watershed" elections next year.

Africa's most populous country and biggest economy will go to the polls in February 2015 to elect a new president and parliament, overshadowed by a five-year insurgency by Boko Haram Islamists who have killed thousands and whose abduction of more than 200 schoolgirls two months ago sparked global outrage.

Nigeria's military indicated on Thursday that it could follow the example of Sri Lanka in fighting terror, to bring an end to an increasingly deadly insurgency by Boko Haram militants.

A high-ranking military delegation from the South Asian island nation, led by Chief of Defense Staff General Jagath Jayasuriya, was in the capital, Abuja, to meet their Nigerian counterparts to share experience and expertise.

Boko Haram violence has forced more than 6,000 people in the northeast Nigerian state of Borno to flee their homes within the last week, the country's main relief agency said on Wednesday.

The National Emergency Management Agency (NEMA) said it had registered 6,227 internally displaced people (IDP) in the state capital, Maiduguri, as of Wednesday.

At least eight people, including three security officers, were killed when gunmen raided three villages in Nigeria's volatile central Plateau state, army and police spokesmen said.

The gunmen launched pre-dawn attacks in Bachit, Rim and Jol villages, they said.

Five people were killed in Boko Haram raids on two villages near a town in northeast Nigeria where more than 200 schoolgirls were kidnapped nearly two months ago, residents said on Wednesday.

Gunmen dressed in military uniform stormed Tohya and Wurojene, 13 kilometers (eight miles) from Chibok, Borno state, late on Monday, opening fire on residents, burning homes and looting food stores.

Suspected Boko Haram gunmen kidnapped at least 20 young mothers near a town in northeast Nigeria where more than 200 schoolgirls were abducted nearly two months ago, sources told Agence France Presse on Tuesday.

There were conflicting reports of how many women were abducted from the nomadic settlement near Chibok in Borno state, with one local leader putting the number as high as 40.

Nigeria's new Muslim monarch, the Emir of Kano, was sworn in on Monday, after a second day of violence fueled by suspicions that politics, not religion, was behind the appointment.

Thousands of well-wishers turned out at the Kano state government headquarters as Sanusi Lamido Sanusi was given his official letter of appointment to the influential role by governor Rabiu Kwankwaso.

Four Nigerian newspapers said soldiers stopped and seized copies of its editions on Friday over security concerns, with one likening the raids to censorship during the country's military rule.

The military confirmed the searches, but officers denied that the moves were designed to muzzle critics, even though at least two of the newspapers had published damning articles about the army in recent days.