A major upgrade is on the cards for the Parliamentary complex.

Parliament's Speaker David Carter has announced the project today.

It will see the construction of two new buildings on Parliament's grounds; a new ministerial building behind the Beehive, and a new building for MPs behind the main Parliament Building.

Mr Carter is not giving specific details on its costs because it would affect tendering processes, but indicates it would be over $100 million.

"We're not prepared to give out any costing, simply because we don't want to reveal the figures that we've worked on prior to the detailed design then going out for tender to building contractors."

The project would see the current $6 million annual lease on Bowen House retained until 2022, by which time construction would be expected to be finished.