The government has not done enough to address the problem of abuses by "gangmasters" recruiting migrant workers to pick farm produce, a committee of MPs has said.

In a new report, the Commons environment, food and rural affairs select committee said it was "very disappointed to find that six years after setting up an inter-departmental working party on the issue, the government appears to be no nearer to establishing the numbers" of both legal and illegal gangmasters.

The cross-party group of MPs warns that the problem is being fuelled by the relationship between farms and the supermarkets that they supply to, due to the intense price competition and short notice given for orders.

"We conclude that the government has failed to confront the problems in the industry," says the report.

"Enforcement of existing legislation is perfunctory and uncoordinated. We were singularly unimpressed by the evidence from Operation Gangmaster, the government's cross-departmental enforcement body.

"The enforcement agencies are insufficiently resourced and lack the political backing to make a significant impact on illegal activity within the agriculture and horticulture labour market."

The Department for Environment, Food and Rural Affairs defended its record.

"The government welcomes the committee's report and will study it carefully. We will respond in full in due course," said a spokesman.

"We recognise the seriousness of the abuses of the law and of workers' rights highlighted in the report, and are determined to tackle them.

"The government is working with several organisations including agricultural labour providers, supermarkets and the Ethical Trading Initiative to draw up a code of good practice for those who supply agricultural labour and to devise an accreditation system for those who abide by these standards."

The spokesman said the committee had only focused on a narrow part of a wider problem.

"The committee's report focuses on agriculture and horticulture but the abuses identified are part of a pattern of unlawful activity affecting many sectors of the economy," he added.

"The government is already taking action to combat these problems, for example, on illegal working by strengthening the powers of the Immigration Service to enter businesses and search records in the Nationality, Asylum and Immigration Act 2002.

"Inland Revenue teams are currently in the process of recovering £4.3 million in unpaid tax and National Insurance contributions from gangmasters from last year.

"We are constantly seeking to improve performance and are evaluating current initiatives."

Shadow environment secretary David Lidington described the report as "damning".

"It splits bare the pretence that we have joined-up government," he said.

"The committee raises very serious concerns about illegal employment and the availability of work permits.

"It is a disgrace that the government has failed to give priority to the issue of gangmasters. As the report makes clear, ministers have gone for spin rather than substance. Defra needs to get a grip of this issue now."

But the Transport and General Workers Union accused the committee of "missing an opportunity" to include a registration scheme of gangmasters in their recommendations.

"We welcome the revitalisation of Operation Gangmaster with clear leadership, budgets and, therefore, accountability as a clear indication that past failures should be tackled," said Peter Allenson, TGWU national secretary for agriculture.

"However, we found it odd that the committee accused the government's approach of being 'piecemeal and inadequate' when they have stopped short of supporting a key solution to the problem."