The "metric martyrs" convicted of selling food in imperial measures will next week take their case to the European Court of Human Rights.

The five traders are due to lodge papers at Strasbourg on Monday in a case backed by the civil rights group, Liberty, which could see Government ministers summoned to explain why they prosecuted a greengrocer for selling bananas by the pound, although it may be years before the case comes to court.

The traders, Steven Thoburn, Peter Collins, Colin Hunt, Julian Harman and John Dove, will use the European Convention on Hu-man Rights to argue their case.

Lawyers plan to refer to the human rights convention's Article 6 which guarantees the right to a fair trial, Article 9 (freedom of conscience) and Article 10 (freedom of expression). They plan to use Article 1 of the convention's Protocol 1, which grants the right to peaceful possession of property - in this case referring to the traders' imperial scales.

On July 15, four of the five were refused leave to appeal to the House of Lords.

Mr Thoburn, 38, was prosecuted by Sunderland City Council on charges of breaching the Weights and Measures Act after selling bananas by the pound. His imperial scales were confiscated and he was given a six-month conditional discharge.