The Glynn Vivian Art Gallery job is the most high profile of several schemes being undertaken by main contractor Opco.

It was also working on a £12m, 10-floor housing block for First Wessex Housing Group in Gosport and converting an orphanage into homes for Persimmon in Bristol.

Jeff Pope, the head of KPMG’s restructuring team in Wales, said the firm had ceased trading towards the end of April and most of its 55 staff had since been made redundant.

Swansea council said it would immediately start the search for a new specialist contractor to finish the £6m revamp of Swansea’s Glynn Vivian Art Gallery.

The job started in February and has another 12 month to run to complete refurbishment of the 1911 building, build a new entrance and re-clad the 1974 gallery extension.

A Swansea council spokesman said: “Swift action is being taken to get a new contractor in place and continue the scheme as soon as possible.

“It’s disappointing that Opco Construction has gone into administration with the loss of a number of jobs, but this landmark project will go ahead in its entirety and within the original budget.

“The process of appointing a contractor will take three months and we expect them to be on site a month later.”

The refurbishment project is being funded by the Welsh Government’s Swansea Regeneration Area programme, the Arts Council of Wales and Swansea Council.