International protests and vigils protest Al Jazeera staffers' detention in Egypt

A members of the foreign media wears black tape across his mouth, to signify the silencing of the media, at a demonstration by Kenyan and Nairobi-based foreign media calling for the release in Egypt of detained Al Jazeera journalist Peter Greste and his colleagues, in Nairobi, Kenya Thursday, Feb. 27, 2014. The protest, part of a global day of action in support of press freedom, called for all journalists jailed in Egypt to be freed but focused attention in particular on Greste, a Nairobi-based correspondent for Al Jazeera who has been in custody in Egypt since Dec. 29, 2013. (AP Photo/Ben Curtis) (The Associated Press)

Protesters, wearing tape across their mouths, to signify the silencing of the media, participate in a rally in support of press freedom, and demanding the release of detained journalists in Egypt, in central London, Thursday, Feb. 27, 2014. The protest, part of a global day of action in support of press freedom, called for all journalists jailed in Egypt to be freed. (AP Photo/Lefteris Pitarakis) (The Associated Press)

A protester wearing tape across her mouth, to signify the silencing of the media, participates in a rally in support of press freedom, and demanding the release of detained journalists in Egypt, in central London, Thursday, Feb. 27, 2014. The protest, part of a global day of action in support of press freedom, called for all journalists jailed in Egypt to be freed. (AP Photo/Lefteris Pitarakis) (The Associated Press)

Journalists and their supporters are joining an international protest against the detention of four Al Jazeera staffers in Egypt.

Media workers and free speech advocates with masking tape stuck across their mouths gathered in places including London's Trafalgar Square, Lebanon's Martyrs' Square and in Kenya's capital, Nairobi.

On the Internet, journalists posted photographs of packed newsrooms bearing signs saying "Journalism is not a crime."

Peter Greste, Mohammed Fahmy, Baher Mohamed, and Abdullah Al Shamy, are among 20 defendants being tried on charges of belonging to and aiding a terrorist organization for their coverage of the Muslim Brotherhood.

They have pleaded not guilty. Al Jazeera says the reporters were merely doing their jobs.

The Associated Press is one of dozens of media organizations which have called on Egyptian authorities to release the reporters.