Teething problems and glitches in the new computer-aided dispatch system placed immense pressure on staff at Sydney and Newcastle centres, Fire Brigade Employees Union state president and Dapto fire station chief Darin Sullivan said.

The system had not been properly tested and crews were being sent to "ridiculous parts of the state", he said.

Just yesterday, the Mercury received reports that the state-of-the-art system had temporarily crashed during the day.

Fire and Rescue NSW (FRNSW) admitted both Sydney and Newcastle "experienced problems" yesterday but said there was "no impact on the receipt of Triple 0 calls and the dispatch of fire trucks to emergencies".

As part of a rationalisation plan, the Wollongong and Katoomba fire communications centres were closed last month, with calls directed to staff in Newcastle or Sydney.

Staff from the Wollongong centre are being retrained this week to resume frontline firefighting duties, mainly at Albion Park.

"The downside is that we've got situations where crews are being called to jobs 800km away," Mr Sullivan said. "They're getting on the radio saying 'do you realise where we are?'

"It's putting a lot of pressure on the system operators - they are feeling very under the pump."

Mr Sullivan said the union was keeping a log of all problems.

"If we find any ... serious threat to the community we will be taking action. The system is not coping very well; it has a lot of teething problems which arguably should have been ironed out before going live."

Union representatives met FRNSW officials to request extra staff be "immediately placed in the centres to alleviate stress levels".

A FRNSW spokesman said yesterday the system had handled 6000 incidents in the first two weeks of its operation and had been "thoroughly tested before it went online" on June 12.

"There were a very small number of anomalies that could be detected only after the system went online," the spokesman said. "These were identified by highly trained FRNSW operators within the first days of the system's use, and immediate action was taken to rectify them.

"It is completely false to suggest that crews were called to jobs hundreds of kilometres away.

"On the first day of operation, there was one isolated example of a geographical error on the system, but the error was immediately noticed by a highly trained operator who corrected it and dispatched the nearest and most appropriate FRNSW crew."

The spokesman said operators had received extensive training and FRNSW had agreed to a union request to extend the time frame for extra support staff at the centres.