The proposal for two offshore patrol craft, and possibly a third, along with one larger extended patrol vessel with an option for a second longrange ship, is expected to be worth more than 210m, according to marine industry sources.

This is a base line figure not including specialist equipment and armaments, and previous estimates put the price tag at between 150m and 190m.

Its understood German ship builder Blohm and Voss is likely to pitch for the contract. Irish naval personnel have visited the firm's shipyard at Kiel to view the construction of a patrol vessel built by it for the Royal New Zealand Navy.

The designs of Australian company Tenix Defence have also been mooted as suiting Irish Atlantic requirements, as well as those of Danish shipyard Moller-Maersk.

The new boats will have increased operational ranges and heavy weather capabilities exceeding the current fleet, which is nearing the end of its 30year working life.

A team of naval service, department of defence and department of finance personnel will assess submissions after the October deadline, and three new vessels are to be delivered on a phased basis between 2010 and 2012.

The government successfully applied to the UN in May to extend its territorial waters by 200 nautical miles and a naval service spokesman said this put extra demands on the fleet, as do climatic changes resulting in increasingly turbulent weather in Irish waters.

"Our geographical area of responsibility has increased, meaning larger patrol areas. A further 300 nautical-mile claim to include the Rockall bank and increased national sovereignty means we need a fleet to survive even harsher conditions."

It is expected that the largest new vessel, probably 120 metres long, will be capable of transporting a detachment of Irish troops or disaster relief personnel with vehicles and equipment. It is not yet clear if this ship will include a helicopter deck.