AMSTERDAM - The Dutch NAM oil joint venture, owned by Royal Dutch Shell and Exxon Mobil, said on Friday it would postpone plans to drill three gas fields near an island off the coast of the Netherlands.

NAM said investigations had shown that only one of the fields near the Ameland island had enough gas to make production worthwhile, and the company would therefore look at other fields in its portfolio to exploit.

Although the amount of gas is interesting in principle, the costs to start production are still relatively high, said Barend Botter, a director at NAM, adding that the plans for the fields could still be resumed in future when costs were lower.

The Netherlands sits on Western Europe's second biggest gas reserves after Norway, and its total known resources at present are estimated at 1,345 billion cubic meters, of which about 86 percent are located onshore, according to government data.

Developers in the Netherlands are also eyeing new ways to exploit gas as traditional resources decline, but they say technological advances and state stimulus measures will be needed for projects to go ahead.

(Reporting by Catherine Hornby; Editing by Keiron Henderson)