Father Christmas has been granted a special licence which will allow him and his team of reindeer to visit homes in those parts of the country still affected by foot-and-mouth disease.

Officials at the Department for Environment, Food and Rural Affairs entered into the festive spirit to soothe the fears of two children living on a farm in Saltburn, Cleveland.

Michael and Sarah Thompson, aged six and four, whose parents run a farm at Moorsholm, wrote to the Farmers Guardian newspaper with their concerns – no doubt shared by children living on farms across the areas still affected by the disease.

Their letter said: "We are very worried that Santa will not be able to come to our farm at Christmas because we both think that he will need a special licence to bring his reindeer.

"Surely once the reindeer have been on one farm, they'll be on a standstill for three weeks and it'll take about 10 years to deliver all the presents.

"So can someone answer our simple question please – does Santa need a licence?"

Vets at Defra's licensing unit in Leeds made a ruling that Father Christmas can make all his visits – provided he lands only on rooftops. As a result, the Disease Control Centre has issued a licence to Mr S Claus which is valid from 24 December 2001. But under the terms of the licence, Rudolph and friends must remain airborne at all times. It states: "If any stops en route involve anything except rooftop landing full C&D (cleansing and disinfection) must be carried out before proceeding."

Reindeer are susceptible to the disease and licensing staff were concerned about the possibility of the virus spreading as Father Christmas has to make multiple visits on Christmas Eve. But his unique airborne delivery system persuaded vets to make an exception.

Brian Woolacott, deputy director of operations at Defra's Leeds office, said: "After the upheaval caused by foot-and-mouth disease you can understand why Michael and Sarah were so worried.

"However, providing that Santa makes his rooftop landings as usual, as specified in the special licence we have granted, they can rest assured that Santa will be able to deliver presents to everyone who deserves them this year.

"He may have to alter his traditional route because the licence does require Michael and Sarah's farm to be the final premises he visits.

"Of the thousands of movement licences we have processed this was certainly the most complex, but we're really happy to have made this vital journey possible."

Michael and Sarah have been sent a copy of the special licence as reassurance that he will visit, Defra said, provided they remain good until Christmas Day.