Provisions for policing Britain's fishing industry are poor, parliament's spending watchdog has warned.

A report published on Thursday called for greater scrutiny of fishing practices and tougher penalties for those breaking the rules.

The National Audit Office said despite some progress more needs to be done to protect British fish stocks.Sustainable stocks of fish are vital to protect the £150 million a year English fishing industry, yet often rogue fishermen who ignored EU fisheries directives slip through the government's nets undetected.

The NAO report acknowledged the "complexity of the task" facing fisheries regulators but said that although regulations met EU standards, there was still room for improvement.

Less than one per cent of vessels from Britain's fleet of over 3000 was found to be checked at sea on a daily basis, while only six per cent of boats had their haul inspected at port.

It was also found that personnel mismanagement had resulted in too few inspectors being available to police fishing in certain areas.

The study said developments such as increased use of satellite technology and new rules specifying exact landing locations for larger vessels had increased the effectiveness of regulation.

But it argued that this success was undermined by the inadequate range of penalties applied to those flouting the rules.

Regulations were infringed "because potential gains may be seen as outweighing the penalties if detected".

Cases brought to trial in 2000/01 had resulted in average penalties only 1.7 times the value of the catch that had infringed the rules.

"The Department for Environment, Food and Rural Affairs has improved the effectiveness of enforcement," concluded NAO chief Sir John Bourn.

"The low chance of prosecution and the potentially high gains, however, may encourage illegal catches and landing of fish, undermining conservation policies."

DEFRA welcomed the report as "fair, balanced and reasonable" and said that a comprehensive review of the NAO recommendations would follow after the report had been examined by the Commons public accounts committee.