Police in Namibia have launched a massive manhunt for 11 prisoners who escaped from a police cell in north-eastern Zambezi region, state media reported.

The trial-awaiting escapees cut through the roof of the Katima Mulilo police station before escaping on Monday, Kisco Sitali, the police spokesperson in the region, told NBC news website.

Pieces of blades and ropes made out of blankets, the items suspected to have been used in the jailbreak, were found in the cell, police said.

Locals have been warned to be vigilant as the escapees are awaiting trial for serious crimes, while one of them is a notorious repeat offender.

"They are very dangerous," Mr Sitali said, adding that one of them was a murder ex-convict.

Police said three of the escapees have already been re-arrested.

More than 100 prisoners who are awaiting trial were housed in the cell, which only has the capacity for 16 people, the state media said.

The cell is said to be under renovation.

Residents have been urged to report any suspicious activities or groups of people to the police.