Spacey, 43, is expected to announce his appointment at a press conference ahead of a fund-raising event at London's Old Vic at midday on Wednesday.

According to newspaper reports, Spacey's tireless fundraising work for the theatre made him a prime candidate for the role.

There is currently no artistic director at the Old Vic, though the position has been held in previous years by Jonathan Miller and Sir Peter Hall.

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Spacey has helped battle to save the theatre, which hit financial difficulties several years ago, since he was appointed to the board of trustees in 1998.

The double Oscar-winning actor is said to be so committed to his role that he flies to London regularly to attend board meetings and stage fund-raising evenings.

Passionate about the London stage and the Old Vic in particular, Spacey has invested more than £100,000 of his own money into saving the venue in Waterloo.

"It continues to be the favourite theatre I've probably ever played in," he said.

Enthralled

Spacey was first introduced to the Old Vic as a child, and has been enthralled with it ever since.

But it was only when he appeared there in The Iceman Cometh in 1998 that he became interested in getting involved in securing its future.

The 1,000-seat venue was saved from property developers by impresario Sally Greene in 1998 but the 180-year-old theatre still needs millions of pounds to ensure its survival.

There are currently plans for a stage version of the hit film Billy Elliot to help raise the target of £10m to save the theatre.

Sir Elton John, the theatre's chairman, is due to attend the fund-raising event with Spacey on Wednesday.

Stars will perform a selection of Sir Elton's hits to raise money for the theatre.