CAIRO, Jan 31 (Aswat Masriya) - Unidentified gunmen killed a police officer in Sinai on Thursday, a police source said.

A lieutenant was driving his car in Meliz area in Sinai when unknown assailants shot him dead, the source told Aswat Masriya.

On Thursday night, military aircrafts targeted the houses of four highly dangerous terrorist elements south of Sheikh Zoueid, the army spokesman said.

Seven extremists were killed and five others were injured during the operation, the spokesman stated.

Extremist militants have intensified attacks against security personnel in Sinai since the ouster of former President Mohamed Mursi last July.