Four more girls kidnapped by Boko Haram militants last month have escaped their captors, the education commissioner for Borno state said on Wednesday, leaving 219 still missing.

The girls were taking exams at a secondary school in the remote northeastern village of Chibok on April 14 when the Islamist gunmen surrounded it, loaded them onto trucks and carted them off. Fifty-three escaped shortly afterwards.

Education commissioner Musa Inuwa declined to give further details of the escape.

(Reporting by Lanre Ola; Writing by Tim Cocks; Editing by Andrew Roche)

(Reuters) -