The raid took place in Royal Street, with equipment belonging to workers from Port Glasgow-based Alex McKay Construction removed.

The builders are in the street renovating a fire-ravaged block of flats.

More than £3,000 worth of specialist tools were taken during the raid, thought to have happened some time between 3.30pm on Friday and 9am on Monday.

Workers say the thieves ‘made themselves at home’ before helping themselves to the expensive equipment.

They arrived on Monday morning to find an empty bottle of wine lying inside and discovered that the heaters had been turned on.

One worker, who didn’t want to be named, said: “The door had been kicked in — it was split in half.

“They’d been drinking inside.

“They came in and put the heaters on — they made themselves at home.

“We’re gutted. We’ll never get the tools back now.” A £500 electric saw, a £400 drill and two angle grinders worth nearly £700 were all taken, along with other items.

The tools had been securely locked away in a reinforced storage unit but the determined thieves forced entry and broke two heavy duty padlocks.

The Royal Street flats have been derelict since being gutted by a fire in July last year.

But they share an entrance close with another block which is in use.

Greenock police are investigating the break-in and today appealed for anyone who saw anything suspicious to get in touch.

Sergeant Allan O’Hare said: “Due to the volume and type of items stolen we believe that a vehicle of some sort will have been used to transport them.

“It may be that local residents have observed persons coming and going from the premises over the weekend thinking it was the workmen.

“I would ask that anyone who has witnessed suspicious activity in Royal Street over the weekend call us on 101.” Workers from Alex McKay Construction have been on site since before Christmas repairing the block of flats.

Nobody from the company was available for comment when contacted by the Tele.