The father of a French jihadist who became an expert bombmaker and was likely killed in US air strikes in Syria has said his son wanted to "die a martyr."

David Daoud Drugeon, 25, is thought to have been travelling in a car in Idlib province when a drone strike hit the vehicle and likely killed him and the driver, a US official and media reports said Thursday.

Speaking to reporters at his home in the western village of Meucon late Thursday,soon after learning from the media of his son's probable death, Patrice Drugeon quoted a letter sent by David in 2010 -- the last communication he had with him.

"We'll see each other again in the afterlife and I will die a martyr," read the letter.

"Dying a martyr aged 25, what for?" Patrice Drugeon asked.

A football fan in his early years, David later drew close to ultraconservative Salafist Muslims, converted to Islam, started learning Arabic and studying the Koran.

After having worked and saved money, he eventually went to Egypt and studied in religious schools there.

He returned to France and at the start of 2010, told his family he was going back to Egypt. But like many other international volunteers, he went down the jihad route and travelled to tribal zones in Pakistan, never to be seen by his relatives again.

There he trained in how to handle explosives and make bombs, and later travelled to Idlib to wage jihad.

David converted to Islam when he was just 13, at a time when his parents were divorcing.

"I saw him convert, but he was moderate," his father said.

"He was baptised, he received a European education, with parents who are Christians, and... he strayed."

"I'd tell parents to really pay attention to their children, to listen to them, to talk to them, to convince them not to join the jihadists because learning about your son's death on the Internet is very hard, and I would not wish it upon anybody," he added.

"I never would have thought he would do this but this is what it has come to now.

"I never would have imagined this would be his destiny and his path."

A US official said it would take time to confirm his death with absolute certainty.