The former journalist and pilot wrote over 25 books including The Odessa File (1972) and The Dogs of War (1974) and sold over 75 million copies worldwide.
Many of his novels were also turned into films.
“Only a few weeks ago I sat with him as we watched a new and moving documentary of his life ... and was reminded of an extraordinary life, well lived,” said Lloyd.
“After serving as one of the youngest ever RAF pilots, he turned to journalism, using his gift for languages in German, French and Russian to become a foreign correspondent in Biafra [in Nigeria],” he said.
“Appalled at what he saw and using his experience during a stint as a secret service agent, he wrote his first and perhaps most famous novel, The Day Of The Jackal,” he added.
A sequel to The Odessa File, entitled Revenge Of Odessa, on which he worked with thriller writer Tony Kent, is due to be published in August, his publisher Bill Scott-Kerr said.
“His journalistic background brought a rigour and a metronomic efficiency to his working practice and his nose for and understanding of a great story kept his novels both thrillingly contemporary and fresh,” Scott-Kerr added.
Forsyth attributed much of his success to “luck”, recalling how a bullet narrowly missed him while he was covering the bloody Biafra civil war between 1967 and 1970.
“I have had the most spectacular luck all through my life,” he told the Times last November in an interview.
“Right place, right time, right person, right contact, right promotion - and even just turning my head away when that bullet went past,” he said.
Asked why he had decided to give up writing - although he later went back to it - he told AFP in 2016 he’d “run out of things to say”.
“I can’t just sit at home and do a nice little romance from within my study, I have to go out and check out places like Modagishu, Guinea Bissau, both hellholes in different ways,” he said.
Forsyth had two sons by his first wife. His second wife, Sandy, died last year.
Conservative MP David Davis paid tribute to his friend as a “fabulous wordsmith”.
He told Sky News that Forsyth “was a great believer in the old values - he believed in honour and patriotism and courage and directness and straightforwardness, and a big defender of our armed forces”.
-Agence France-Presse