The reopening of Aberdeen Art Gallery has been delayed by at least a year.

A £30m revamp of the building began in 2015 and was scheduled to be completed in late 2017.

The gallery will now not open to the public until late 2018 or early 2019.

Aberdeen City Council has not revealed the reason for the problem but councillor Marie Boulton called it "unacceptable".

"High-level discussions with the main contractor for the redevelopment, McLaughlin and Harvey, are ongoing to finalise a revised schedule for the project," said Ms Boulton, who heads up cultural projects for the council.

"This is an important project for Aberdeen and it is imperative that what will be a lasting legacy for the city is completed to the exacting standards required for a development of this significance - but a delay of this nature is unacceptable."

Problems with a leaking ceiling were responsible for earlier construction problems at the gallery.

The reopening of Provost Skene's House has also been delayed until at least next year.

The 400-year-old building near Marischal College was intended to become a museum showcasing the achievements of famous Aberdonians.

The local authority said "options are to be considered" following the results of a building survey, which have also not been disclosed.

Ms Boulton added: "Protecting Aberdeen's built heritage is a priority for the council and it is important that the latest information is taken into account."

The construction of an art warehouse in Northfield that had been expected to open before work on the gallery began was also hit a series of delays.

It was expected to open in late 2014 and cost £3.6m but a series of issues pushed the final budget up to more than £6m, as revealed by STV News.

Politicians were warned of the need for a council-owned storage facility as far back as 2009 but the warehouse did not open until late 2016.