Nine inmates were killed in a botched prison break in the Democratic Republic of Congo on Sunday after one of them pulled the pin of a grenade but didn't throw it, a police official said.

The incident follows a rash of prison violence and escapes in the central African country, including the escape of nearly 1,000 detainees from a high security jail in September.

Grenade
"The civilian (prisoner) did not know how to use a grenade, he pulled the pin out but didn't throw it," the provincial chief of police, General Gaston Luzembo, told Reuters.

He said 50 people were wounded in the incident in a prison in the eastern city of Bukavu, and that an investigation was looking into how the inmate had got the grenade.

Luzembo added that a jailed ex-colonel appeared to be among the masterminds of the attempted escape.

A Reuters witness said the early morning blast at the jail was followed by gunfire and some inmates who had suffered serious injuries were being treated at a local hospital.

Overcrowded
Prisons in the Congo, which the United Nations ranks as one of the least developed countries in the world, are known for overcrowding, tough conditions and shoddy security.

Eastern Congo remains deeply unstable more than eight years after the end of a civil war, with rebels and members of the armed forces both accused of widespread criminality.

Source: Reuters