Perth and Kinross Council has insisted its headquarters revamp is on schedule despite announcing Watergate in the city centre is to remain shut for a further two months.
The local authority said the extension is needed due to additional stonework repair which is being undertaken at 2 High Street.
The road, which links High Street with South Street, was closed at the north end on September 21.
The south end of the one-way street has been opened to two-way traffic to allow for continued access to a car park and other buildings.
It was anticipated the thoroughfare would reopen on December 21 but the council has announced restrictions will remain in place until February 29.
A spokeswoman for Perth and Kinross Council said: “There is no impact to the overall 2 High Street refurbishment programme as a result of this request for an extended road closure.
“The intention of Morrison Construction had been to remove scaffolding prior to Christmas but additional stonework repairs are meaning the scaffolding will have to be retained until this revised date in February 2016.”
Earlier this year the council said the £9.7 million project was on budget.
Council staff moved out in January to temporary accommodation at The Atrium on Glover Street, with council committee meetings being held at Dewar’s Centre.
It is understood the council headquarters will be completed by Christmas next year, in a move designed to save money and allow the public to access services more easily.
The scheme has already seen waste services, roads, parking and licensing payments and applications move into the council building at Pullar House, Perth.
A row broke out last month over plans to move the council meeting rooms from the top floor of the building to ground level, at a cost of £850,000.
The move, which was dubbed a “vanity project” by one critic, was approved at a special meeting of Perth and Kinross Council last week, despite strong resistance from Conservative members.