Domestic air travellers could take a plane from a third airport on Melbourne's south-eastern fringe under a new strategy to be released today.

Planning Minister Matthew Guy is expected to release a discussion paper today that flags a third airport, claiming road traffic is choking Melbourne Airport at Tullamarine.

Tooradin, south of Cranbourne, is listed as an option for the new airport in the Metropolitan Planning Strategy discussion paper, the Herald Sun has reported.

Business groups have previously suggested Tyabb and South Gippsland as locations for a third airport.