Nigerian troops said Friday they had killed nine suspected members of Islamist terrorist group Boko Haram in a gunfight in the country's northeast.

"In a midnight encounter with Boko Haram insurgents, troops of the 7 division Nigerian Army killed nine Boko Haram terrorists while others fled with various degrees of injuries," army spokesman Colonel Muhammad Dole said in a statement.

Nigerian police on Friday said they had arrested more than 200 people suspected of "criminal motives" as they prepared to head to a state holding a crunch vote for its next governor.

"We have arrested some 181 strange-looking people loitering around in Owerri", the capital of Imo, state police commissioner Mohammed Katsina said on local Channels television.

Boko Haram is holding a French priest who was kidnapped in northern Cameroon, a source in the banned Nigerian Islamist group said on Friday, rejecting claims of a rift among the insurgents.

"I can confirm that the French priest is in the hands of mujahideen (fighters) from Jamaat Ahl al-Sunna Li Da'wat al-Jihad, who carried out the operation that was coordinated with Ansaru," he told Agence France Presse.

More than 37,000 people have fled violence between the army and Boko Haram insurgents in northern Nigeria for neighboring Niger, the United Nations said Wednesday.

According to the latest report from the U.N. Office for Humanitarian Affairs (OCHA), "37,332 people fleeing clashes in the states of Borno, Yobe and Adamaoua in the north of Nigeria (...) have been registered in Diffa, southeast Niger".

The United States on Tuesday announced the release of two Americans kidnapped by pirates off southern Nigeria in October.

"We welcome the release of the two U.S. citizens who were kidnapped from the Retriever," State Department spokeswoman Jen Psaki said.

Police in Nigeria's capital on Tuesday blocked an anti-corruption meeting by sealing off the hotel conference room where activists had planned to gather, a rights group and a hotel employee said.

Crackdowns on civil society organizations, common in some African countries, have become rare in Nigeria in recent years.

Nigerians in three northeastern states under emergency rule broadly support the extension of special powers designed to quell the Boko Haram insurgency that has claimed thousands of lives.

Yobe, Borno and Adamawa states first saw a massive influx of troops in May this year and a communications black-out to tackle militants who want to impose a harsh form of Islamic law in the region.

Nigeria requires more regional help to tackle Boko Haram militants in its restive northeast but the country is likely to have to shoulder most of the burden on its own for now, according to analysts.

A senior Nigerian military official last week urged neighboring Cameroon to do more to help tackle the Islamist insurgency, which has claimed thousands of lives since 2009 and caused international concern over its potential to spread.

Gunmen attacked five farming villages in volatile central Nigeria's Benue State, killing six people and burning many houses, police said Sunday.

"Five Agatu villages were attacked yesterday by suspected Fulani cattle herdsmen who killed six people," state police spokesman Daniel Ezeala told AFP.

Nigerian security forces staged lethal raids Saturday on suspected Boko Haram insurgents in the northern city of Kano allegedly plotting "suicide attacks" there and in the capital Abuja, the military said.

Five suspected "terrorists" and two soldiers died in gunbattles during the swoop on two addresses in Kano conducted by elite troops and domestic intelligence officers, military spokesman Captain Iweha Ikedichi said in a statement.