Legislation to create a supermarket watchdog should be put before Parliament immediately as MPs are being "under-employed", farming leaders have said.

A Bill for the introduction of a retail adjudicator is needed urgently to police the grocery supply chain, say Westcountry farmers who are fed up with poor payments from both retailers and processors.

MPs from all parties have complained they have little to do as major Government legislation including slashing benefits and NHS reform is stuck in the House of Lords.

The National Farmers' Union (NFU) has called on the Government to bring forward a draft Bill to establish a groceries code adjudicator as a matter of urgency, with the aim that the official should be in place by the end of this year.

At present, there is no Parliamentary timetable to get the Bill through both houses, with the Queen's Speech in April the earliest many expect it to emerge despite the lack of activity in the Commons.

The Groceries Supply Code of Practice came into force in February 2010, but still no monitoring or enforcement body has been put in place.

The previous Labour Government had advanced plans for an ombudsman, which were shelved following the change of administration.

NFU South West regional director, Melanie Squires, said: "We continue to hear of suppliers being squeezed ever tighter by the major supermarkets, damaging the long-term prospects of primary producers, as well as the interests of consumers.

"The Government has committed to introducing an adjudicator and last year published a draft Bill setting out its proposals.

"We have some concerns about the powers that will be available to the adjudicator and have made clear to the Government how we believe the Bill can be improved. But without an actual Bill, these arguments are entirely academic. It is no secret that the House of Commons is currently under-employed with regard to the amount of legislation passing through the Chamber. We believe that, given the cross-party support for the adjudicator, and the fact that two select committees of MPs have already examined the draft Bill, there is no reason the formal Bill can't be introduced during the final months of the current Parliamentary session."

Andrew George, Liberal Democrat MP for St Ives, said: "The call for a supermarket watchdog has cross-party support and there can be no excuses for further delay. Every day that goes by means that more food producers go out of business due to bully-boy tactics of supermarkets.

"The progress of this campaign has been met with constant opposition from some of the large supermarkets. If they have nothing to hide then they have nothing to fear."