France said on Thursday it had imposed sanctions, including travel bans, on 18 Saudi citizens linked to the murder of Saudi journalist Jamal Khashoggi and warned that more could follow depending on results of the current investigation.

"The murder of Mr Khashoggi is a crime of extreme gravity, which moreover goes against freedom of the press and the most fundamental rights," the foreign ministry said in a statement.

"France asks that all light be shed on the manner in which such an act may have been committed. It expects from the Saudi authorities a transparent, detailed and exhaustive response."