Ireland, joined by other EU nations, on Monday demanded sanctions against Iceland and the Faroe Islands for over-fishing, the latest chapter in an ongoing "mackerel war."

Backed by France, Portugal and Spain, Ireland asked the European Commission for information on potential trade measures against their north Atlantic neighbours.

EU fishing states are angry at high quotas set unilaterally by Iceland and the Faroe Islands, an autonomous Danish territory, on the grounds that global warming is pushing more mackerel north into their waters.

The European Commission reckons mackerel fishing this year will be 36 percent higher than levels deemed to be sustainable for the stock.

In January 2011, Brussels said it would block fishing boats from Iceland -- which is negotiating to join the 27-nation group -- from unloading mackerel in the EU until a dispute over quotas was resolved.

About two months earlier, after quota talks failed, Iceland unilaterally raised its mackerel quota to 146,000 tonnes for 2011 from about 130,000 tonnes in 2010 -- an enormous level compared to 2,000 tonnes in previous years.

The increases came as Iceland's economy, which is now largely fishing-based, was trying to get back on its feet after its major banks collapsed in 2008.