A gunman killed himself after bursting into a Manila casino, firing shots and setting gaming tables alight, Philippine police said, sowing panic in a country on high alert after martial law was declared in the south.

Police said earlier the man's motive was likely robbery and that the incident was not terror-related.

National police chief Ronald dela Rosa told DZMM radio the lone gunman had not aimed his assault rifle at people at the Resorts World Manila entertainment complex during the hours-long drama that began shortly after midnight (1600 GMT), and may have been trying to steal casino chips.