Lebanon's Saad Hariri, who resigned as prime minister over the weekend, is “free to move around”, French Foreign Minister Jean-Yves Le Drian claimed on Friday amid rumours he was being held against his will in Saudi Arabia.

Drian told Europe-1 radio on Friday that “to our knowledge” Hariri is not being held by Saudi authorities.

“He went to Abu Dhabi the day before the President [Emmanuel) Macron's visit [on Wednesday] so we think he's free to move around, and it is up to him to make his choices,” Le Drian told Europe 1 radio.

“The Lebanese situation is the most worrying subject of the moment,” Le Drian added in his interview.

Le Drian's office wouldn't say where the French information came from, but his statements come a day after French President Emmanuel Macron's surprise visit to Riyadh. Macron discussed Lebanon, a former French protectorate, during his overnight trip which saw him attend the inauguration of the new Louvre museum in Abu Dhabi.

Hariri abruptly announced his resignation last week in a television appearance from Saudi Arabia, and has not returned to his country since. In his speech he said he was stepping down because of Iran's “grip” on Lebanon and threats to his life, but the comments led to immediate speculation about Saudi pressure.

Al-Akhbar newspaper, which is close to Iranian-backed movement Hezbollah, suggested that Hariri, who holds Saudi nationality, was being held “hostage” in Riyadh.

Lebanese Foreign Minister Gebran Bassil on Thursday had demanded the return of Hariri from Saudi Arabia.

Hariri's announcement raised fears that Lebanon ─ split into rival camps led by Hariri and Hezbollah ─ could once again descend into violence amid an intensifying proxy war between Saudi Arabia and Tehran, who have long vied for influence in Lebanon.

Lebanon “was moving towards a new solution with a new constitution, elections to come. The departure of Prime Minister Hariri creates new uncertainties,” Le Drian said in his interview.