Two French investigative journalists have been charged in Paris with trying to blackmail the king of Morocco, legal sources said Saturday.

Eric Laurent and Catherine Graciet, who have been held since Thursday, were released on bail, the sources said.

The pair, who are working on a book about King Mohammed VI, were arrested after a meeting with a Moroccan official at which they were given money, a source close to the French investigation told AFP, confirming remarks made by a lawyer for the Moroccan government.

"A sum of money was handed over and accepted," the source said, adding that the journalists were being investigated for attempted extortion and attempted blackmail.

Eric Dupond-Moretti, a lawyer for the Moroccan government, told RTL radio that Laurent contacted the royal palace in July, saying he was writing a book about the king.

The journalist allegedly demanded three million euros ($3.4 million) in hush money not to publish the book, which reportedly contains damaging revelations about Mohammed VI.

Graciet's lawyer, Eric Moutet, confirmed the existence of a "financial deal" but said his client had been caught in a  "trap".

The publisher, Editions du Seuil, confirmed that the pair, who already have one title about the Moroccan leader under their belt, were working on another book slated for publication "in January/February".