BRUSSELS (REUTERS) - EU governments unanimously approved a new law to slash the use of plastic grocery bags on Friday, hoping to curb litter on land and a spreading "plastic soup" in the world's oceans.

The measure, drafted with the European Parliament, has been criticised by the new EU executive.

It says states may struggle to implement legislation which proposes using minimum prices or other methods to cut bag numbers by 80 per cent in a decade.

That was echoed by a trade body for the plastics industry.

It favours an end to supermarkets giving bags away free, a measure already applied in some countries.

But it said a patchwork of national rules could impede EU trade.

Member state envoys endorsed the plan to give governments a choice of either banning free plastic bags, or setting binding targets to bring the average annual consumption of lightweight bags below 90 per person by the end of 2019 and 40 by December 2025.

The Commission's first vice-president Frans Timmermans said this week the executive supported efforts to cut bag use that has created a "plastic soup", but warned governments they would have to be able to enforce the new law.

If states do not comply, the Commission can take them to the bloc's highest courts, which have the power to impose fines.

The average EU citizen used 176 plastic bags in 2010, few of which were recycled.

That figure is similar to in other rich economies, including the United States, where local initiatives have also been taken to curb use of lightweight plastics.

Some EU states will need to take no action since pricing measures have already produced reductions of up to 90 per cent.

Danes use an average of only four light plastic bags a year. Poles and Portuguese use 100 times as many, EU data show.

Danish Greens lawmaker Margrete Auken, who negotiated for the European Parliament, called the new law "an historic breakthrough".