Lebanese authorities have denied a French expert on jihadists entry to the country and accused him of links to extremist groups, diplomatic and security sources said Tuesday.

Romain Caillet, a 37-year-old researcher with the French Institute for the Near East, rejected the claim and suggested Lebanon's powerful Shiite movement Hezbollah was responsible for his expulsion.

A French embassy source said Caillet, who had been based in Lebanon for five years, was "turned away on Sunday... at Beirut airport when he tried to return from Morocco.

"No explanation of the reason for his expulsion has been provided to us," the source said, speaking on condition of anonymity.

A high-ranking source at Lebanon's general security agency said Caillet was suspected of involvement with extremists.

"Under the cover of his work, this individual was suspected of being linked with terrorist organisations," the source aid.

Reached by telephone in France, Caillet confirmed he was turned away while returning from Casablanca, after being held for several hours.

He said the accusations of links to extremists were made because "I make statements or provide analysis that displease some circles in Lebanon.

"If every person who meets jihadists for interviews or research is suspected of terrorism, that's a lot of people. I will continue to work from France," he said.

On his Twitter account, Caillet laid the blame on Hezbollah.

"What do they accuse me of? Daring to speak of the influence of Hezbollah and its pro-Iranian allies on all of Lebanon's institutions," he wrote.

"The murderers of researcher Michel Seurat and Rafiq Hariri wanted me to leave Lebanon so my work will continue elsewhere."

Seurat, a sociologist, was kidnapped in Lebanon in 1985 and died in captivity. His abduction was claimed by the Islamic Jihad group, a branch of Hezbollah.

Five members of Hezbollah are being prosecuted by an international tribunal for the assassination of Hariri, a former prime minister who was killed in a Beirut bomb blast in 2005.