This article was reproduced with the kind permission
of the British Broadcasting Corporation
26 November 2007, 16:59 GMT
The city's Telephone House has been hit by three separate fires in little more than a month.
A blaze damaged the upper floors of the office block on Saturday and police have not ruled out a connection to two fires on the same day last month.
About 30 people were evacuated on Saturday night as firefighters battled the blaze in the six-storey building.
A police spokeswoman said the investigation into Saturday's fire was at an early stage.
Officers visited the building to see if they could determine whether the fire was set on purpose.
It was an intense fire and they took a lot of punishment in there
A spokesman for BT said they would pass CCTV tapes from Saturday night to the police.
He said the swipe cards employees use to enter the building give the telecommunications company a record of everyone who was in Telephone House on Saturday.
Tayside Fire and Rescue group manager, Stewart Edgar, said: "The crews that dealt with the fire were heroic in their own way.
"It was an intense fire and they took a lot of punishment in there."
The alarm was raised shortly after 1900 GMT when BT employees working in the building smelled smoke.
A worker said: "We were just working on our computers when this smoke started billowing in and we were all told to get out.
"It's not that busy on a Saturday night but I reckon there would have been about 30 to 40 people, all call centre staff, working inside.
"At first we didn't know where the fire was coming from but we have been told that it was on the floors above us. It's strange because there is nobody up there on a Saturday night."
At one stage, there were about 50 firefighters at the scene, manning six pumping appliances and other equipment.
Ambulance crews were called but no one was injured.
Fire and rescue area manager, Mick McKay, said: "When we arrived there was a lot of heavy smoke and flames from the fifth and sixth floors of the property.
"We committed nine crew members wearing breathing apparatus into the building. There is an internal dry riser system, and the fire was extinguished using two jets."
Developed in the 1970s, Telephone House has six floors of open-plan office accommodation.
Last month, the building was at the centre of a forensic investigation after two fires broke out during the same evening, one in a lift and the other in a fifth-floor toilet.