Economic affairs minister Henk Kamp is set to further cut gas extraction from the Groningen fields in the second half of this year, sources in The Hague have told broadcaster Nos.

Kamp earlier cut production by 4.5 billion cubic metres over the first six months of this year because of the risk of earthquakes. He is now poised to limit full-year production to 30 billion cubic metres, Nos says, and is expected to inform parliament of his decision on Tuesday.

Earlier on Monday the Financieele Dagblad said the most severe earthquake likely to hit Groningen province in the coming years will be 4.5 on the Richter scale, not 5 as earlier forecast.

The TNO research institute evaluated the risks on behalf of the economic affairs ministry to take into account the earlier reduction in gas extraction.

The quakes are caused by the ground settling after the gas has been removed.

The strongest earthquake so far to hit Groningen measured 3.6 on the Richter scale and took place in August 2012. The new maximum forecast is still 10 times as strong as this, the Financieele Dagblad points out.