The United States is deploying 300 armed US military personnel to Cameron to conduct intelligence, surveillance and reconnaissance operations.

In a letter sent to Congress, President Obama said an advance force of 90 troops have been sent to the country last Monday to help counter the violent extremists group Boko Haram, according to USA Today.

The letted stated that the forces will be armed, "but only for the purpose of providing their own security and not for offensive military operations. They will stay in the country until their support is no longer needed.''

Obama's letter also stated that the troops have been deployed at the invitation of the Cameroon government.

A statement released by a defence department spokesman said the military personnel will support ISR (intelligence, surveillance and reconnaissance) flights being conducted in the area "to better enable African partners to secure their borders against violent and illegal activities disrupting our common desire for stability in the region,'' Aljazeera reported.

"Most importantly, all information collected by US unarmed, remotely-piloted aircraft is used to support international counter-violent extremist organisation operations,'' it said.

White House spokesman Josh Earnest meanwhile said the US had offered its "unique capabilities'' to assist with the regional effort.

"This is obviously a unique capacity that the United States has to bring to bear to this effort and it will be used in support of the ongoing regional counter-extremist efforts that are ongoing there,'' said Earnest.

Cameroon has reportedly become a target of Boko Haram militants since backing the Nigerian military in its fight against them.

Some two weeks ago, two female suicide bombers killed nine people and injured 29 others in an attack at Kangaleri town in northern Cameroon.

At least 50 civilians had been killed after a series of brutal attacks made by Boko Haram in Cameroon, Nigeria, Niger and Chad, USA Today said.

In May last year, the United States deployed 80 military personnel along with surveillance aircraft to Chad as part of an effort to find more than 275 Nigerian schoolgirls kidnapped by Boko Haram militants. Many of the girls have not been found, and since then the group has pledged its allegiance to the Islamic State group operating in Iraq and Syria, the report said.

The attacks in Nigeria and neighbouring countries over the past months form part of the group's plans to implement Islamic law in the region. The group has seized large area in the northeast where it also declared a caliphate.

Boko Haram, which means Western education is forbidden, was founded in 2002 but only launched its military operation in 2009.

The group has declared that it is joining the Islamic State jihadist group in the Middle East and called itself as the ISIS caliphate's "West African province.''