International human rights lawyer Amal Clooney will help lead a British-Canadian push to defend journalists from attacks and restrictions around the world, ministers say.
She was named co-chair of a legal panel that will draw up proposals to counter laws that hinder reporters.
"Those with a pen in their hand should not feel a noose around their neck," the British-Lebanese barrister told an event on the issue at a G7 meeting of foreign ministers in France on Friday.
More than 60 journalists were killed in 2018 according to Reporters Without Borders, more than half of them targeted deliberately, with the murder of Saudi columnist Jamal Khashoggi in particular drawing international condemnation.
Britain's Foreign Minister, Jeremy Hunt, told the event that democratic states needed to make it "an international taboo of the highest order" to murder, arrest or detain journalists for doing their jobs.
Hunt, who appeared alongside his Canadian counterpart Chrystia Freeland, also named Clooney as his special envoy on media freedom.
"When journalists are not able to question those in authority, hold them to account, freely and with impunity then you start a slippery slope to the closed societies that none of us want to see growing in influence," he said.
"The media has a crucial role to play in holding the powerful to account. There is no escaping the fact that draconian and outdated laws around the world are being used to restrict the ability of the media to report the truth.
"Amal Clooney's leading work on human rights means she is ideally placed to ensure this campaign has real impact for journalists and the free societies who depend on their work."
The wife of Hollywood A-lister George Clooney lawyer said she was "honoured" to have been given the role.
Last year, Clooney joined the legal team representing two Reuters journalists who were convicted under Myanmar's official secrets act and sentenced to seven years in prison.
On Friday, she said only one in 10 countries enjoyed a free press.
Referring to the Khashoggi's murder, she said: "Many more such crimes go unreported and too many also go unpunished."
The legal panel, she added, could propose reforms of national laws that run counter to international standards, such as blasphemy legislation, and encourage governments to give journalists more consular protection abroad. The proposals will not be legally binding.
Khashoggi's death sparked global outrage but human rights groups criticised the meek response of many Western capitals, many of which cited the importance of trade relations for not adopting a tougher stance with Saudi Arabia.
