Boko Haram
Boko Haram is estimated to have killed at least 2,053 people since the start of 2014 Reuters

Cameroon's president Paul Biya has announced that 27 Boko Haram hostages have been released.

Biya said the hostages, including vice-prime Minister Amadou Ali's wife and 10 Chinese workers, were safe following months of captivity after being kidnapped in May and July near Cameroon's border with Nigeria.

"The 27 hostages kidnapped on May 16, 2014, at Waza and on July 27, 2014, at Kolofata were given this night to Cameroonian authorities," Biya said on state radio.

"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."

In July, Cameroon said Ali's wife and maid were captured in a "savage attack" on his home in the northern town of Kolofata by Boko Haram militants. Ali managed to escape to a neighbouring town.

Earlier this year, Cameroon agreed to form a 2,800-strong regional force with Nigeria, Chad and Niger to tackle Boko Haram.

The Islamist militant group sparked international outrage in April, when it abducted more than 200 schoolgirls in the north-eastern Nigerian village of Chibok.

Nigerian president Goodluck Jonathan was severely criticised for his slow response to the kidnapping and for the lack of information communicated by the government to the public.

Former Nigerian president Olusegun Obasanjo also expressed his frustration at the lack of progress of negotiations between the government and Boko Haram.

Last month, Nigerian police said one of the kidnapped girls was released after being dropped off by suspected Boko Haram militants at Mubi in Adamawa state, some 100km (60 miles) from Chibok.

One parent, who declined to be named, told Reuters: "She was found running in a village. She was in the bush for about four days. She's still receiving medical attention."

According to Human Rights Watch, Boko Haram has killed at least 2,053 people since the beginning of 2014.