A manhunt's under way in Auckland for Kael Leona - over the fatal stabbing of a woman on a moving bus in Onehunga yesterday

Police say 37-year-old Leona was last seen wearing a dark sweatshirt with white writing, and a black backpack.

He had a pale green T-shirt tied on his head, and was wearing dark trousers and white sports shoes.

Court documents reveal Leona was due in court today, for obstructing a police officer.

Acting Detective Inspector, Alisse Robertson says it appears the victim and suspect - did NOT know each other.

She says they were travelling on the bus close together for some time, but a motive is still unknown.