The Greens have announced a plan to fast track the construction of high speed rail on the Eastern Sea board.

Australian Greens Leader Senator Christine Milne and Deputy Leader Adam Bandt MP have announced the plan at Melbourne's Southern Cross Station and Mr Bandt will outline details of the plan to a conference on high speed in Sydney on Wednesday.

As part of the agreement to support the minority Labor government, the Australian Greens secured a $20 million feasibility study into high speed rail.