The government has taken emergency powers to restrict access to the countryside and has extended the ban on the movement of livestock as the number of cases of foot and mouth disease continues to rise.

With 22 outbreaks now confirmed, Tony Blair has chaired an emergency meeting of ministers at Downing Street to discuss the crisis. The meeting of ministers from across Whitehall and the devolved assemblies examined how the government should respond to spread of the disease.

The four latest cases were confirmed by the chief veterinary officer Jim Scudamore on Wednesday. Officials are also investigating the first suspected case in Northern Ireland. The four new cases were at two farms in Powys, Wales; a farm at Llangowan, Herefordshire; and at an abattoir near Preston, Lancashire.

Agriculture minister Nick Brown announced that the ban on the movement of livestock in the UK would be continued for a further two weeks, beginning this Friday. The European Commission has given its backing to the ban following a meeting of the Standing Vetinary Committee. The commission issued a statement saying: "The implementation of a complete standstill is a painful but necessary measure, which is supported by all member states. The European Commission and member states welcome the measures taken by the United Kingdom and appreciate the close and effective co-operation between their services."

He also confirmed that £152 million has been set aside as compensation for farmers directly affected by the disease and that experts are working on a system that may allow some strictly controlled movements of livestock to holding areas or slaughterhouses.

The Ministry of Agriculture, Fisheries and Food has also introduced statutory powers enabling local authorities in England and Wales to close footpaths and rights of way in order to control any potential spread of the disease. The Scottish Executive will be taking similar powers.

Speaking on Tuesday, Nick Brown also advised the public to avoid any unnecessary visits to farms.

"Today we have taken powers to ensure that this advice can be enforced where appropriate on individual premises, in local authority areas where disease has been confirmed, and in other local authority areas with the specific approval of MAFF," he said.

The disease has now been detected in 17 farms in Northumberland, County Durham, Lancashire, Wiltshire, Essex, Devon and Anglesey.

Speaking on Monday the chief veterinary officer, Jim Scudamore, said the spread of the disease could be halted. "With everyone's co-operation we can eliminate this disease," he said.

Sport has also been hit by the spread of the disease. Horse-racing has been suspended until March 7, the Wales-Ireland Six Nations rugby international has been postponed and the Rally of Wales, which was due to take place on March 10 and 11, has been called off.

As a further precautionary measure, the Countryside Alliance has announced that is has postponed its planned march on London which had been scheduled for March 18. It had been feared that the mass movement from rural areas to the capital could have further spread the virus which causes foot and mouth disease.

Their announcement followed the decision to stop fox-hunting and other countryside sports in the wake of the foot and mouth crisis.

The president of the National Farmer's Union, Ben Gill, repeated his call for the public to stay away from the countryside and said he would be raising the issue in a meeting with the prime minister on Monday evening. He said: "This outbreak has potentially catastrophic implications for the British farming industry."

The outbreak of the disease has, say Westminster insiders, effectively ruled out an April 5 election - and could call into question the favoured May 3 date.

Speaking in the Commons on Monday the Labour MP Tam Dalyell said an election would be irresponsible in the current climate. He told MPs: "How should I respond to the farmer who exploded that it would be grossly irresponsible of the politicians to hold a general election in this situation with people trampling around the countryside?"