SCOTTISH Opera's £14 million revamp of its Theatre Royal home will not be completed until ­December, seven months behind schedule.

Fresh snags have hit the construction of the building's new foyer and it will not now open to the public until just before Christmas.

The landmark foyer was originally meant to open in May, and then July, but further delays have forced the postponement of the new addition's grand opening.

Shows in the theatre will continue as planned, as they have throughout the building process.

These include performances of La Cenerentola, Cinderella Unwrapped for Scottish Opera, the play Dangerous Corner, Matthew Bourne's Edward Scissorhands, and shows Jeeves and Wooster and Top Hat.

Alex Reedijk, general director of Scottish Opera, said: "The contractors at the Theatre Royal are signalling that they need a little more time to finish the building - five or so weeks - which means we are now hoping to welcome the public into the new foyer in December. All performances at the theatre will continue as planned, as they have throughout the building project."

It is not known what effect the delay will have on the costs of the revamp. The building of the dramatic extension to the venerable theatre had been slowed last winter by bad weather, as well as ­problems caused by its tight site on the corner of two busy Glasgow streets, and unexpected issues with the fabric of the Theatre Royal building.

The new foyer, which features a gold coloured covering now in place and a dramatic spiral staircase, was designed by architects Page/Park. A large tapestry by the leading Scottish artist Alison Watt will hang in the new building.

The contractor for the building work is Sir Robert McAlpine.

The cylindrical addition also includes a roof terrace, bars and cafes as well as new entrances to the main theatre auditorium. The new foyer has commanding views of north and west Glasgow from its roof terrace and is being built on to the north end of the Theatre Royal.

Earlier this year Mr Reedijk said the extended timetable on the construction of the extension would ensure it was of the ­"highest quality".

He then said: "Essentially it is the joining an old building to a new building, and any time we looked at that back wall, the north gable, there was another thing we had not expected. It is a 150-year-old wall that's had so many interventions over the years, it's had so many uses, interventions, apertures opened and closed, and particularly where we have been physically joining old and new together we have bumped into so much."

Other problems have included finding unexpected power cables under the pavement outside the Theatre Royal, which had to be dug up and relaid.

The fitting of the glass windows in the complex cylindrical design has also proved to be problematical. Space restrictions at the 480 square metre building site have presented their own problems.

Mr Reedijk said in July: "The site is bound on two sides by two busy roads, you are backing onto a jolly old building and a brand new building. You cannot block off the road [Hope Street] and we can only work on Cowcaddens Road on certain hours of the day. So that has slowed it down a little bit."

Scottish Opera is searching for a new musical director following the departure of Emmanuel Joel-Hornak.