The government will prosecute farmers who fail to abide by the strict foot and mouth disinfection rules, ministers have warned.

The statement comes as it emerged that attempts to halt the spread of foot and mouth disease may be being hampered by farmers who are flouting disinfection rules in areas badly affected by the foot and mouth epidemic.

Health and safety officials in North Yorkshire are said to be alarmed that farmers are ignoring the regulations governing the disinfection of farms in areas affected by the foot and mouth epidemic.

In North Yorkshire alone over 150 breaches of the regulations have been uncovered over the last week.

Eighty farms out of 1100 inspected did not have the right facilities for disinfection. Other breaches included farms without foot washes outside entrance gates or buckets full of mud or the wrong chemicals

The discovery is prompting fresh fears that the disease may spread to pig farms in an area now cordoned off as a "bio-security zone". The latest three cases of the disease have been in North Yorkshire.

Trading standards officers in the area, which has been heavily hit by foot and mouth disease, have found that more than one in 10 farm vehicles had not been properly disinfected before leaving premises affected by the disease.

Animal Health minister Elliot Morley said drivers who failed to observe the rules would face prosecution. The maximum penalty under the Animal Health Act on conviction in a magistrates court is a fine of £5,000.

"The majority of farmers and those who work with livestock in the Thirsk area have worked very hard to comply with strict biosecurity measures to stop the spread of foot-and-mouth disease and I welcome their co-operation and commitment. The majority of the livestock sector knows how important it is to keep up their guard at a time when the disease is confined to a few hot spots," he said.

"I am determined that the minority who are flouting these important measures do not endanger the majority. Our checks have revealed a considerable number of infringements. For the first few days we have just been pointing this out to farmers and drivers, but we now need to take a harder line. In future farmers and drivers who fail to comply with the biosecurity requirements are likely to be reported for prosecution.

Morley said he was "determined" there would be no biosecurity failures within the area under patrol within 30 days.

The National Farmers Union has warned farmers that they must abide by the rules whether their farms have been hit by foot and mouth outbreaks or not.

Rob Simpson, NFU's north east regional spokesman, said: "The vast majority of farmers are abiding by the bio-security measures. However, there is minority who are not - whether that is because of recklessness or a lack of information we do not know."

Simpson believes many farmers are still confused as to the exact procedures they need to follow in order to ensure compliance with the disinfection rules.

"I have spoken to one farmer who has been given conflicting advice from DEFRA officials. If it is the case that farmers are not getting specific advice from officials when they ask for it then I would implore DEFRA to rectify that."

Farmers have been hit by claims that they are deliberately dropping their guard in order to cash in on generous compensation payments. The NFU strongly denied the claims, saying it had not heard of a single case where foot and mouth disease had been spread recklessly.