Brad Pitt and Peter Capaldi in Glasgow School of Art fire appeal

Pitt is an admirer of Mackintosh art and Capaldi is a former student of Glasgow School of Art

Hollywood star Brad Pitt and Dr Who actor Peter Capaldi are leading efforts to raise £20m to restore Glasgow School of Art's fire-hit Mackintosh building.

Both have agreed to be trustees of The Mackintosh Appeal which the art school (GSA) officially launched on Wednesday.

Pitt is a well-known fan of Charles Rennie Mackintosh, the Scots architect who designed the iconic building. Capaldi is a former art school student.

GSA estimates the cost of restoring the building to be between £20m and £35m.

The blaze, which destroyed about 10% of the building, including the Mackintosh library, broke out on Friday 23 May.

In the immediate aftermath, GSA established a Phoenix Bursary scheme to help students affected by the fire to recreate lost work.

Glasgow School of Art will seek to raise £20m to help restore its iconic Mackintosh building

The initiative attracted a £750,000 contribution from the Scottish government, which has also pledged £5m in match funding towards the restoration costs. The UK government has also said it will make a contribution.

Capaldi, who studied graphic design at GSA and graduated in 1980, said he hoped funds could be raised to restore the Mackintosh building "to its former grace".

"It always seemed to me, when I studied there, both as a student and as a child in Saturday morning art classes, an exotic place of the imagination... all nooks and crannies, guarded by stern ancient statues and full of artistic possibilities," he said.

'Rise from the ashes'

"There is no greater symbol of the artistic spirit of Scotland than the Mackintosh building.

"But more than that it is a symbol of where art belongs, rising as it does out of the heart of a great city. A mighty castle on a hill, it is a part of me, and of all Glaswegians."

In a specially recorded message for the students Capaldi said: "I'm so sorry for all of you who have lost your degree shows.

"All I can say to you is that you are artists. This will only add to your story. You will be reborn, and rise from the ashes even stronger."

Pitt's love of Mackintosh's work is well known and he visited the architect's Hill House in Helensburgh, in the 1990s, returning again with wife Angela Jolie in 2011 while filming World War Z in Glasgow.

GSA director, Professor Tom Inns, Pitt and Capaldi would have an important role to play in the fundraising appeal.

He said: "We are delighted that both Peter Capaldi, one of our most celebrated alumni, and Brad Pitt, whose admiration for Mackintosh is well known, have both joined our campaign and will be Trustees on The Mackintosh Appeal."

Prof Inns said the immediate priority for the art school had been the impact on students but it was now time to look forward.

"We have been overwhelmed by the offers of support from around the world since the fire and are hugely grateful to all those people who have donated," he said.

"This support, along with that of the Scottish government, has been vital. It has enabled us to put in place the Phoenix Bursaries programme to help those students who were most affected by the fire."

"We are now beginning to look forward to the work we will need to do to return the Mackintosh building to its former glory, and to make sure it continues to be a fit and inspiring place for our students to make work."