Shayeb went on hunger strike on Wednesday after a Palestinian court extended his initial 48 hours detention for 15 days.
Palestinian Foreign Minister Riyad Malki and the head of the diplomatic mission to France, Hayel Al-Fahoum, are suing him following an article implicating both in a corruption scandal.
He was first arrested and questioned for eight hours in January following the publication of the piece.
“We condemn the exorbitant size of the damages being sought by the plaintiffs – six million dollars (4.5 million euros) – and the court’s decision to keep Shayeb in police custody for another two weeks," Paris-based Reporters Without Borders said in a statement Friday. "We also urge the Palestinian judicial system to respect Shayeb’s right not to reveal his sources, a right that is recognised by Palestinian law."
The article, published in the Jordanian newspaper Al Ghad, alleged that Malki coverd up corruption within the Palestinian diplomatic mission in France and that other senior members of President Mahmoud Abbas's Fatah and the Palestinian Authority were complicit in the scandal.
It also claimed that members of the mission had attempted to recruit Palestinian students to spy on Islamic groups in France.
A group of journalists have declared a boycott of the Palestinian foreign ministry and the Palestinian Authority’s Freedom of Speech Award in support of his case.
The Palestinian diplomatic mission in France confirmed to Reporters Without Borders that Fahoum is suing Shayeb for libel.
“All we are asking of the prosecutor general is to investigate this case and to convict us if Shayeb’s claims prove to be true and to convict him if his information proves to be false, defamatory and insulting,” Malki told the al Ma'an news agency.
The International Press Institute (IPI) says that since the beginning of 2012, at leat five journalists working in the Palestinian territories have been subjected to arbitraty arrest.