Harper Lee's To Kill a Mockingbird is currently fifth in the race, with Orwell's Nineteen Eighty-Four, AA Milne's Winnie the Pooh and Joseph Heller's Catch-22 among the others in the top 10.

All online, text and interactive voting methods have closed, but phone vote lines will stay open until Saturday.

"We hope we get the same enthusiasm as we have so far in the project," a BBC spokeswoman said.

Over the past seven weeks, the top 21 books have been championed by celebrity fans.

'One horse race'

The live results coverage will include a countdown from number 21 to number five, and then a more detailed look at the five most popular books.

Comedy troupe Reduced Shakespeare Company will perform skits based on the books.

Bookmakers Ladbrokes closed bets in October because The Lord of the Rings had become the only real contender in "a one horse race".

"Nobody wanted to back anybody other than Tolkien, we couldn't continue betting on a one horse race and were forced to close the book and take the losses on the chin," a spokesman said.

'Under siege'

Odds for the Lord of the Rings had opened at 5-1.

"Tolkien fans are amongst the best organised group of supporters on the internet and for two days, our website was under siege," the spokesman said.

Book-selling internet site Amazon.co.uk reported the project - which originally shortlisted 100 novels - boosted sales of some books by nearly 500% after the list was announced on 18 October.

Winnie the Pooh led the upsurge, with sales up 474% while demand for The Lord of the Rings went up 400%.

Book chain Waterstone's said sales of Philip Pullman's His Dark Materials trilogy rose 342% after being featured on the show.