The Finnish Navy has been given the go-ahead to begin a program to replace six combat ships.

The program is called Flotilla 2020 and will lead to the procurement of four vessels. The ships will replace four Rauma-class fast attack missile craft and two Hameenmaa-class mine-layers.

Both classes of ships date from the 1990s and their life-cycles "cannot be extended in a cost-efficient way," the Ministry of Defense said.

"The main task of the Navy is to secure the maritime connections vital for the Finnish society and therefore the new vessels shall have the capacity to monitor and secure territorial integrity, protect maritime transport and counter naval attacks," it said.

"To be able to carry out these tasks, the vessels shall be able to monitor maritime areas above and under the water surface and in the airspace and to use weapons to counter potential threats of enemy forces. The exact configuration of the battle system will be decided in the course of the planning process.

The project planning phase will take place in 2015-2018. The building phase is anticipated to take place between 2019-2024.

Finland's Defense Forces estimate the cost of Flotilla 2020 at about $1.3 billion but allocation of funds would be a matter for parliament.