Image copyright Getty Images Image caption Cussler wrote more than 80 books in total during his lifetime

Clive Cussler, the US author of the popular Dirk Pitt novels, has died at the age of 88.

He wrote 25 books in the adventure series, including Sahara and Raise the Titanic, and sold more than 100 million copies of his novels in total.

Writing on Twitter, Cussler's wife said: "It is with a heavy heart that I share the sad news that my husband Clive passed away [on] Monday.

"It has been a privilege to share in his life."

She added: "I want to thank you, his fans and friends, for all the support. He was the kindest most gentle man I ever met. I know, his adventures will continue."

The cause of his death has not been confirmed.

'Soft spot in my heart'

Cussler's 1992 thriller Sahara was adapted for the big screen in a 2005 film starring Matthew McConaughey and Penelope Cruz.

The writer, whose books have been published in more than 40 languages, was married to Barbara Knight for nearly 50 years until her death in 2003, and they had three children, Teri, Dirk, and Dayna.

He later married Janet Horvath. His son Dirk, named after the character, co-wrote his final three novels.

"Dirk will always have a soft spot in my heart because he started if off," Cussler said in an interview with Working Mother in 2013.

"I hope readers see Pitt as a normal, average guy who is down to earth. He likes the Air Force, tequila, and an occasional cigar.

Image copyright Getty Images

"I used myself as a model for Dirk. We are both 6'3", have green eyes, and at that time were the same weight and the same age."

He added: "The only differences are that he is better with the girls and he has aged about 10 years while I have aged about 50."

After selling the Sahara story to the billionaire Philip Anschutz, Cussler later sued, telling a US court in 2007 Hollywood "tore the heart out" of the book.

The movie grossed $119 million (£92.1m) worldwide but was still considered a box-office failure as it failed to recoup its own filmmaking costs.

The novelist said the company broke its contract by changing the story without his consent.

"I thought it was just awful," he said of the film, adding that he considered the re-written dialogue to be silly.

Image copyright Getty Images Image caption Cussler, pictured in 1977, was born in Illinois

One his earlier works, Raise the Titanic! was also made into a movie in 1980. The film, starring Jason Robards, Richard Jordan, David Selby, Anne Archer, and Sir Alec Guinness, proved to be a similar flop.

Cussler wrote more than 80 books in total, including the Isaac Bell Adventures and Fargo Adventures series.

Known as an expert in shipwrecks, Cussler founded the non-profit National Underwater and Marine Agency.

His non-fiction book Sea Hunters was so extensive in its underwater knowledge the Maritime College in the State of New York gave him a doctorate.

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