UK- A writer who claims “The Da Vinci Code” copied from his work insisted in a British court on Wednesday there were specific echoes of his book in the best-selling thriller.

However, Michael Baigent conceded there were many differences in detail between “The Da Vinci Code” and his 1982 nonfiction book “The Holy Blood and the Holy Grail,” but he said the similarities were “fairly specific.”

John Baldwin, a lawyer for Da Vinci Code publisher Random House, read passages from the novel out loud in London’s High Court to stress the differences from the earlier book, which proposed that a secret order called the Priory of Sion existed to preserve the bloodline founded by Jesus Christ and Mary Magdalene.

“There’s no mention of the Priory’s oath to keep its true nature hidden in ‘The Holy Blood and the Holy Grail,’ is there?” Baldwin asked. Baigent replied: “No. I concede that.”

“There’s no mention of the Priory protecting the tomb of Mary Magdalene, is there?” Baldwin asked.

“Not explicitly, no,” said Baigent.

Baigent and his co-author Richard Leigh are suing Random House for infringing the copyright of their book. They claim Dan Brown’s blockbuster “appropriated the architecture” of their work, which explores theories that Jesus married Mary Magdalene, that the couple had a child and that the bloodline survives.

If the writers succeed in securing an injunction to bar the use of their material, they could hold up the scheduled May 19 release of “The Da Vinci Code” film starring Tom Hanks.

Random House lawyers have done their best to demolish the authors’ claim in court, arguing that the ideas in dispute are so general they are not protected by copyright.

Random House attorney John Baldwin also said many of the ideas in “The Holy Blood and the Holy Grail” did not feature in Brown’s book, a mixture of code-breaking, art history, religion and mystical lore that has sold more than 40 million copies since it was published in 2003.

Under cross-examination on Tuesday, New Zealand-born Baigent admitted that he had exaggerated claims that “The Da Vinci Code” borrowed from his work.

Baldwin questioned his claim in a written witness statement that book reviews agreed Brown had used a thriller plot to disseminate the central theme of “The Holy Blood and the Holy Grail.”

Baigent replied: “I think my language was infelicitous, and I think I have to agree with you on that.”

The exchange was watched by Brown, who is attending the case and is expected to take the stand later in the week.

The third author of “The Holy Blood and the Holy Grail,” Henry Lincoln, is not involved in the case. A lawyer for the plaintiffs, Paul Sutton, refused to say why he was not participating.

Lincoln, who is in his 70s and reportedly in poor health, could not be reached for comment.