Cameroon's president Paul Biya has said that 27 hostages, including 10 Chinese workers, held by suspected Boko Haram militants have been released.

Also freed was the wife of Cameroon's Vice-Prime Minister Amadou Ali. President Biya said that the hostages, seized in May and June close to the Nigeria border, were safe.

Boko Haram is seeking to establish an Islamist state in Nigeria but its fighters often cross the long and porous border with Cameroon.

Many Nigerian civilians in border towns have fled to Cameroon to escape Boko Haram attacks, which have been stepped up in recent months. In June, Cameroon, Nigeria, Chad and Niger agreed to form a 2,800-strong regional force to tackle Boko Haram militants.

Cameroon has reinforced its troops in its northern regions. President Biya said in a statement on state radio: "The 27 hostages kidnapped on May 16, 2014, at Waza and on July 27, 2014, at Kolofata were given this night to Cameroonian authorities.

"Ten Chinese, the wife of the Vice Prime Minister Amadou Ali, the Lamido (a local religious leader) of Kolofata, and the members of their families kidnapped with them are safe."

No details were given on the circumstances of the release.