The plan was presented for parliamentary approval earlier this month.
The investment, to be exclusively financed by the private-sector, will "create infrastructure to exploit offshore renewable energies along Portugal's mainland coast, in Madeira and the Azores", according to the document drawn up by the planning and infrastructure ministry.
It also includes the expansion of Portugal's only existing offshore floating wind facility at Viana do Castelo and "the installation of submarine cables to connect offshore production plants with the national grid".
In November 2017 the government published "an industrial strategy and action plan for offshore renewable energy" which predicted that offshore renewables, principally floating wind turbines, could satisfy 25% of electricity demand and reduce energy imports by 20%.
The industrial strategy aims to make the expansion of offshore capacity the base for an industrial sector generating €254 million in inward investment and creating 1500 new jobs.
A spokesman for EDP Renovaveis, the principal partner in the consortium which is developing the 25MW Windfloat project at Viana do Castelo, told Windpower Monthly he was "not authorised to provide figures about investments in our projects".
He said he was "unaware at the present moment of any plans to develop other offshore project in Portugal".