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.

One soldier was wounded late Thursday in the clashes in Damboa area of Borno state, he said.

"During the encounter, arms and ammunitions were recovered and two pick-up vehicles were destroyed."

His claim could not be independently verified.

He said that troops had intensified patrols inside the forest areas of Damboa and nearby Gwoza with a view to preventing further attacks by the insurgents.

The United States designated Boko Haram and an offshoot known as Ansaru as terror groups on Wednesday following four years of horrific attacks that have claimed thousands of lives.

On Friday the group said it was holding a French priest kidnapped in northern Cameroon.

Meanwhile, the Nigerian government said Friday in a statement by the foreign affairs ministry in Abuja that the United States' designation of Boko Haram and Ansaru as foreign terrorist organisations would strengthen ties between the two nations.

"It will strengthen cooperation between Nigeria and the United States in the fight against international terror, enhance the capacity and legal basis for concerted actions against both groups," the statement said.

The designation would also "enable the two countries to work more closely towards reducing the capability and capacity of the groups to unleash terror," it added.

Nigeria, Africa's most populous nation, said it would welcome "more support and assistance from the international community along the lines of the US position on these groups".