Firefighters in Northern Ireland have joined an unofficial strike spreading across the UK and are answering only emergency calls.
Crews were sent home without pay
The action has been taken in support of colleagues in Greater Manchester who have been suspended because of their refusal to use a new piece of equipment.
They said the action was because the employers failed to honour a 3.5% pay deal agreed last November.
Speaking on Wednesday, Jim Quinn of the Fire Brigade Union said emergency calls would be answered as usual.
"The public won't know any difference. We will respond to all calls promptly and efficiently," he said.
"What it does mean is that issues like training and station administration will stop henceforth.
"The employers have still to pay 3.5% from last November. The members are very frustrated and angry."
Later on Wednesday evening, a spokesman for the Northern Ireland Fire Brigade said: "We are aware of some sporadic unofficial industrial action within the Northern Ireland Fire Brigade at this time, however we would reassure the Northern Ireland public that emergency cover is being provided as normal.
"National negotiations are taking place to resolve the overall pay issues and we are hopeful for a satisfactory outcome."
Crews in a number of brigades are answering 999 calls only in response to the suspension of 19 firefighters in Salford.
The firefighters said they had not received an agreed pay rise and refused to use new anti-terror equipment.
The dispute quickly spread to parts of Yorkshire, the West Midlands, Wiltshire, Gloucester and Tayside.
Jim Quinn said emergency calls would be answered as usual
The Fire Brigades Union has told the BBC that the crews in Avon and Cornwall could also take action.
There is also no fire cover in the Broughton area of Greater Manchester, after crews walked out in protest about the treatment of the Salford crews.
Following agreements made in June last year for a staged 16% pay rise, which settled the UK-wide dispute from the previous year, fire crews were expecting to get a rise in November.
However, the FBU says the pay rise has still not been received and so it has withdrawn from the agreement.
Firefighters in Wales last week refused to operate the anti-terrorist equipment, leading to warnings that unofficial action could escalate.
A spokeswoman for the Office of Deputy Prime Minister John Prescott, which has responsibility for the fire service, said: "There is no justification for any such action, which could put lives and property at risk."
She said discussions between the union and employers was still on-going.
"But the union and its members must recognise that the June 2003 settlement
made payment of salary increases dependent on progress in modernisation and this will be put in jeopardy by further industrial action," she added.