THE revamp of Scotland's National Gallery will be completed by 2020 and cost more than £17m, its director general has declared, as he revealed a 2018 exhibition season featuring some of the biggest names in the arts world.

An extensive, and exclusive, show about Rembrandt, as well as the first major Scottish exhibition for the leading contemporary painter Jenny Saville, are among the significant attractions next year at the galleries.

Sir John Leighton, director general of the National Galleries of Scotland (NGS) said that depsite the re-think of the plans for the National Gallery, which was announced in March this year, he still hopes the redevelopment will be done by 2020.

However, he would not estimate the total cost, although he expects it to be more than the previously stated £16.8m.

The cost of the project is likely to be affected by the impact of Brexit, the rising cost of construction industry in Edinburgh and raw materials, he said.

"It's definitely going to happen, it is full steam ahead," he said.

The revamp will double the exhibition space at the National Gallery on The Mound, create a new facade, and involve a rehang of the entire building, with Scottish art displayed alongside the gallery's famed international art.

The NGS are ready to re-submit planning permission and hope to send the plans out to tender in the New Year.

Sir John said: "I have learnt my lesson from last time, I am not saying anything about the schedule or the price until we get the figures back from the market, but we are still working to an end date of 2020 for re-opening and I am still hoping to win some time back.

"I hope that this time next year there are spades in the ground and contractors onsite, that is my aspiration."

The project has £5m from the Heritage Lottery Fund and £2m from the Scottish Government, as well as "several million" from an American tour of art.

He noted it is a "complicated project" and added: "I will not give a figure for the total cost until the tender prices are in.

"But the original figure was £16.8m and it will be more than that, but how much more I don't know, we will try and keep it as close to that as possible."

He added: "It will not be a tear-jerking figure, we are still using that as our baseline."

The summer show about "Britain's love affair" with Rembrandt will be the landmark exhibition at the Scottish National Gallery next year.

Rembrandt: Britain's Discovery of the Master, will reveal how the "taste for Rembrandt’s work in Britain evolved over the past 400 years."

It will bring together key works by Rembrandt which remain in British collections as well as paintings now overseas.

Rembrandt: Britain’s Discovery of the Master, will open on 7 July and run until 14 October.

The large-scale summer exhibition at the Scottish National Gallery of Modern Art (SNGMA) in 2018 will be a major survey of the career of the German Expressionist artist, Emil Nolde (1867-1956).

Emil Nolde: Colour is Life, will comprise about 120 paintings, drawings, watercolours and prints.

During the Nazi rule of Germany, Nolde was branded a ‘degenerate’ artist and forbidden to work as a professional artist.

The third instalment of NOW, a three-year series of contemporary art exhibitions currently running at the SNGMA, will open on 24 March 2018, and feature a presentation of works by renowned painter Jenny Saville.

Saville graduated from Glasgow School of Art in 1992 and has enjoyed success over the past 25 years.

She is best known for her paintings which depict the naked female form on a large scale.

This will be the first museum exhibition of her work ever to be staged in Scotland and will feature work from her graduation show at the GSA, as well as at least one new work.

Victoria Crowe: Beyond Likeness, which opens at the Scottish National Portrait Gallery next spring and runs until November 2018, will bring together a group of portraits by the distinguished Scottish artist.