Thailand's king has spoken publicly for the first time since deadly street protests in Bangkok.

King Bhumipol has sworn in a group of new ministers after a cabinet reshuffle by prime minister Abhisit Vejjajiva.

He told the ministers to follow their oaths and work with honesty and dedication, but he has made no explicit comments about the political violence.

Mr Abhisit reshuffled his cabinet due to a rift in the coalition after the dispersal of the anti-government rally.

He has also announced former attorney-general Kanit Nankorn will head an investigation into the violence.

The law professor also headed a probe into alleged extra-judicial killings under former prime minister and Red Shirt icon Thaksin Shinawatra.

The Red Shirt-aligned opposition disagreed with his appointment.