This article was reproduced with the kind permission
of the British Broadcasting Corporation
28 November 2007, 17:59 GMT
The RMT said the fire alarm and evacuation system had not worked properly since July.
In one fire alert, the alarm did not sound in several parts of the station, the RMT said. The union has now lodged a formal complaint.
Network Rail, which owns and runs Leeds Station, said there was "no fault with the fire alarm or evacuation system".
A spokesman said it had fully investigated the RMT's complaint and found it to be "groundless".
He said: "The station operates a phased evacuation system so the alarm does not sound throughout the entire building on every occasion.
"Staff at the station are being re-briefed to remind them of how the system operates.
"An earlier issue with the audible alert in the travel centre was resolved as soon as it was discovered and was not due to a fault."
But Allen Heath, of the RMT, stood by the union's claims.
He said: "We are talking about the first class lounge at Leeds - a huge big area.
"We are talking about the travel centre at Leeds, again a big area where a lot of people work and a lot of people could be at risk.
"It is just not good enough, it is not acceptable and we are not standing for it."