Two arson attacks have brought down parts of BT's network in and around Manchester.
It appears that several man-hole covers were lifted up during the night and wheelie-bins full of ignited petrol poured down them.
According to local sources, nine points of presence (POPs) have been sabotaged at two locations in the Salford Quays district. Local police are now investigating the attacks.
A BT spokeswoman told silicon.com: "There was obviously malicious intent. The fire in the manholes caused cables to melt, meaning there is network congestion in the area."
BT has engineers at the sites and has admitted at least three other operators that use its network have been affected. Trunk traffic is being re-routed using the telco's network centre in Oswestry, Shropshire, as fibre SDH backhaul links have been lost.
However, the greater problem may prove fixing local networks used for ADSL provision and other BT services over copper lines.
One customer said: "Word is that it was a deliberate attack on sub-stations in the middle of the night. It really started to bite at about 7:00 this morning when people started turning up for work."
Malcolm Greenaway, another BT customer and director of IT and Internet firm Aquae Vitae, said: "We've already had an earthquake and storms this week, which have caused minor damage, but now this. I think it's affected a lot of businesses up here."
Greater Manchester Police have confirmed two attacks, one at 2:50 a.m. at Trafford Road on Salford Quays and one at 4:00 a.m. on Ordsall Lane in Salford. They said enquiries into the incidents, which also knocked out a traffic lights box, are ongoing.