An oil or petrol spill in Melbourne’s Yarra River has prompted authorities to issue a chemical hazard alert for some inner-city suburbs.

The spill was spotted this morning near Victoria Bridge, between Richmond and Hawthorn, a Metropolitan Fire Brigade (MFB) spokeswoman said.

The source of the spill has not yet been determined. (9NEWS)

A hazard warning has been issued. (9NEWS)

The hazardous incident team are now on scene trying to contain the spill and determine its source.

People have been urged to avoid using the river in Abbotsford, Burnley, Hawthorn, Kew and Richmond.