Workmen are today expected to begin removing an unstable chimney brick by brick from a fire-ravaged Bury St Edmunds building.

Speaking yesterday, a spokeswoman for St Edmundsbury Borough Council said the chimney stack at Cupola House, home to Strada restaurant, in The Traverse, could fall either way.

Four businesses remain shut on the Buttermarket – Nationwide, Lloyds Bank, Specsavers and Phones 4u – while the chimney is deemed to be dangerous.

And on the nearby Cornhill, protective scaffolding has been installed at the Halifax Building Society, Harriet's cafe and Laura Ashley to allow them to re-open.

The council spokeswoman said overnight on Tuesday engineers had carefully removed rubble from Skinner Street – at the back of Cupola House – but in doing so, they uncovered an unstable wall which needed to be secured before further work could continue.

It is joined to the main chimney and there is a risk it could bring the whole stack down.

Workmen using a crane with a cage will allow the main chimney stack to be reduced by hand to roof level so the wall can then be untied from the chimney in a controlled way.

This work is weather dependent as the equipment cannot be used in wet and windy conditions, and it may take until the weekend to be completed.

Load-bearing scaffolding is also due to be installed at the front of Cupola House today.

A spokeswoman for English Heritage said: 'The building is in a very fragile and potentially unstable state and it is still too early to say exactly what can be saved, but we are encouraged by the swift erection of the scaffolding which seems to suggest that there is hope that the surviving fabric can be rescued.'

The fire – which began just before 9pm on Saturday in the basement – was still smouldering yesterday. The spokeswoman for the borough council, which has taken over as lead agency for the recovery phase, said putting out the fire was a priority as well as salvaging any material that can either be re-used or used as templates and getting all the remaining closed businesses open.

A Bury St Edmunds Town Council spokeswoman said they were 'greatly appreciative' of the work of the emergency services and the borough council.

Seven people have had to find alternative accommodation due to the fire, the cause of which is not believed to be suspicious.

A whiteboard with up-to-date information is positioned outside Croasdales pharmacy. Also visit www.stedmundsbury.gov.uk. The fire service remains in attendance.