Update A fire on the fourth floor of Belfast's Telephone House tore through a BT data centre, burning the customers of affected ISPs, as well as those seeking to access several government websites.

The major incident – which is not being treated as suspicious – was attended by several fire crews, backed up by six fire engines, an "aerial appliance" (a glorified cherry-picker) and a command support unit at 05:08 this morning.

Eight fire fighters, garbed in breathing apparatus, were sent into the building to attack the fire, which was successfully extinguished.

"Today's incident disrupted the power supply to the data centre only," said a BT spokesman, and "no customer data or equipment was damaged", adding that "a number of customers were affected".

Asked whether BT is concerned that this issue might affect its other data centres, the telecoms giant responded with a resounding "no".

A blog post from ISP Tibus stated that the damage was limited to a single room. However, that room houses the connectivity equipment feeding the main data centre space.

Reports of a major fire at the data centre we use in Belfast. Unclear of extent of impact to services. More to follow. — Tibus (@tibus) June 24, 2015

Our website is currently unavailable. Please call 02890 828604, or email us at info@policeombudsman.org if you need any help or information — Police Ombudsman NI (@PONIPressOffice) June 24, 2015

Tibus' blog continued:

Our biggest concern is around the re-application of power to our own cabinets (these physically house servers). An ungraceful power re-provision process can cause damage to the delicate hosting gear that we (and all service providers) use to provide services. We are trying to get assurances from BT on their timescales and their plans for power re-supply.

Although nearby buildings were evacuated during the operation and the attending fire engines caused rush-hour traffic delays, a BT statement describes the fire as only being "small".

The Register has contacted Tibus and will update this article when we hear back. ®

Update

BT have come back to us with a comment on the fire, which reads as follows: "Today's incident disrupted the power supply to the data centre only. No customer data or equipment was damaged. A number of customers were affected."

At least no-one could accuse them of hyperbole.