Greece is hoping to build a floating fence to run across the Aegean Sea in a bid to prevent migrant crossings to the Greek islands from Turkey.
The fence, which will be 2.7 kilometres (1.7 miles) in length, will be netted and will rise 50 centimetres (20 inches) in order to hold flashing lights.
It will cost an estimated €500,000 to build, including four years of upkeep.
The Greek Defence Ministry has now opened the project for bidding from private contractors to supply the barrier, which it says it would like to be installed within three months.
It needs to be "with non-military specifications", the ministry said, with "specific features for carrying out the mission of [maritime agencies] in managing the refugee crisis".
The project comes as part of the new Greek government's move to fulfil its promise to take a tougher stance on illegal migration.
In 2019, almost 60,00 migrants and refugees reached the Greek islands, which was almost double the number recorded the year before, according to the United Nations' refugee agency.