Up to 200 homes in south Tyrone have been left without phone services after hundreds of metres of valuable copper cable was stolen.
Around 600 metres of cable is thought to have been cut down and stolen in the early hours of Wednesday by thieves.
According to BT, there was significant damage caused to two major cables at the junction of the Tamnamore Road and the Clonmore Road, close to Clonmore village.
A spokesman for the company said; "Significant damage has been caused, by vandals, to two major BT cables situated on the junction of the Tamnamore Road and the Clonmore Road, in the Dungannon area. This has resulted in a break in normal service for a number of local residents and businesses.
"Extensive underground repair work is in progress and engineers will remain on site until full service is restored to all those affected. BT security is currently investigating the cause."
It said it hoped to complete repairs on Thursday night or Friday morning.
Sinn Fein's Francie Molloy, who lives close to where the theft took place, said he was concerned the incident may lead to copycat incidents.
"It's a rural area and it looks as if it has been taken for copper. It's a crazy situation. Clonmore isn't the sort of place where this kind of thing normally happens.
"It probably is opportunistic and I wouldn't want it turned into a copycat situation with the rising prices for lead and copper. Someone could be killed with live cables - even with telephone cables there's still a danger."
With copper prices at an all-time high, the thefts of pipes and tanks from vacant houses have been on the rise over the last year as well as copper wiring also being stolen across Northern Ireland.
Last month a forklift was used to steal a copper boiler tank from the Royal Victoria Hospital in Belfast and four men were arrested at Carn Industrial Estate in Portadown as part of a planned police operation on copper theft.