Farmers have been urged to check their field sizes after the Rural Payments Agency began updating maps of England this week.

The Country Land and Business Association said farmers should look at field maps carefully and identify any problems promptly to help avoid the fiasco that occurred last time the RPA carried out its mapping procedure.

Thousands of farmers were left struggling to claim their single payments after the agency first carried out its mapping in 2005.

Old data from ordnance survey maps and wrongly-calculated parcels of land meant the RPA’s implementation of the single payment scheme was dubbed a disaster by the industry.

The RPA said it had sought to iron out problems with the previous system and a pilot of the scheme carried out on over 1000 Leicestershire farms had been successful.

The latest mapping system, which began this week in central England and is expected to be completed by the end of the year, will use data from 2008 OS maps, as well as aerial photography and data from single payment forms, it said.

Farmers who disagreed with their maps could contact an RPA helpline or arrange to meet an agent to rectify any problems, it added.

But the CLA said it was “quietly sceptical” that things would run smoothly.

Claire Collyer, CLA conservation adviser, said it was vital farmers checked the accuracy of their field maps within the 28 days specified by the RPA.

“Last time was hideous,” she said. “It seems like the RPA is trying to do the right thing, but our biggest concern is the 28-day deadline.

“It’s fine if you own one farm and you’re not in the middle of harvest. But for bigger estates or for agents with hundreds of clients, it will be a logistical nightmare.

“If you don’t reply the RPA will assume the map is right.”

Ms Collyer said she was concerned about farmers being able to get a meeting with an RPA official if too many people had issues with their maps.

“For the time and money needed to get things right, it’s all extra costs for businesses.”

An RPA spokeswoman said the agency had made it easier for people to respond and get help with their maps.

“We are urging farmers to look carefully at them and let us know if they have a problem; these maps are to help them,” she said.

“If people need further help we can provide it. We think we have made it easier for them.”