THE author of blockbuster novel The Da Vinci Code is facing a second lawsuit over plagiarism claims.
Dan Brown denies he lifted material for his international best-seller from another book.
Rival author Lewis Perdue has brought the copyright action at a court in New York, claiming Brown lifted plot material from two of his books - The Da Vinci Legacy and Daughter of God - and used it in The Da Vinci Code, which has sold more than 12 million copies worldwide.
But Brown is already suing Perdue for making the plagiarism accusations.
Brown is also being sued by authors Michael Baigent and Richard Leigh, who claim he has "lifted the whole architecture" of the research they carried out for their non-fiction work The Holy Blood and the Holy Grail, which they co-wrote with Henry Lincoln.
The phenomenal success of the murder mystery novel has seen visitors flock to Rossyln Chapel in Midlothian, where key scenes of the book are set.
Brown, a 39-year-old former English teacher from New Hampshire, said the plagiarism claims in the latest case were nonsense.
"We anticipate that the action shall be summarily dismissed," said Elizabeth McNamara, the lawyer for Brown and his publisher, Random House.
But Perdue insisted there are too many similarities between the whodunits to be a coincidence.
Judge George Daniels is set to issue a ruling in the spring.
Baigent and Leigh’s lawsuit claims at least $150,000 (80,000) damages for breach of copyright, saying a "substantial" amount of their work has been used and asking that copies of The Da Vinci Code be destroyed.
Sir Leigh Teabing is a central character in The Da Vinci Code, but the name combines Richard Leigh’s surname and an anagram of Baigent, and Sir Leigh’s physical description is said to be similar to The Holy Blood’s third co-author, Henry Lincoln.
Baigent and Leigh claim that the novel’s premise and chunks of factual research are plagiarised from their original historical hypothesis, which has sold more than two million copies despite being denounced by several Church commentators as "pseudo-history".
The Holy Blood and the Holy Grail was based on six years of research and hypotheses that Jesus married Mary Magdalene and founded a royal bloodline protected by a series of esoteric societies including the Knights Templar and the Priory of Sion, one of whose "Grand Master" heads is claimed to have been Leonardo da Vinci. The authors argue that Brown lifted their all-important list of the Grand Masters, who supposedly guarded the secret documents pertaining to Christ’s bloodline, without acknowledgement.
Brown used the 15th century chapel at Rosslyn for key scenes because of its links with the ancient Knights Templar order and tales of the Holy Grail.
Filming for the Da Vinci Code, a blockbuster featuring Harrison Ford and Tom Cruise, is to start in the chapel in May.
In July last year, a record 9029 people visited the 15th century chapel - a 96 per cent increase on the previous year.
Work began last April on a 4 million preservation scheme which is expected to be completed in 2008.