MANILA — An air and ground assault by Malaysian forces killed at least 13 of the nearly 200 militants seeking to reclaim part of Borneo Island for a Filipino sultan, Malaysian police officials said Wednesday.

Sporadic fighting continued on Wednesday in remote coastal areas of the eastern Malaysian state of Sabah as the police and soldiers scoured rugged territory, searching house to house to find Filipino rebels who escaped the large assault on Tuesday. At least 40 people have died so far in the fighting.

The Malaysian state news agency, Bernama, said the police warned on Wednesday that some of the rebels were “impersonating as members of the public.”

“The mopping and searching will cover a wider area given there are signs the intruders moved to another location,” Chief Ismail Omar of the Royal Malaysia Police told reporters on Wednesday, without providing more details.