Al Jazeera is calling for a Global Day of Action to demand the immediate release of four of its journalists who have been locked up in Egypt's prisons for months.

People in more than 30 cities will express their solidarity and support on Thursday, with public events taking place in Sydney, Manila, Islamabad, Doha, Amman, Nairobi, Ankara, Berlin, London, Rio, Montreal, Washington DC and San Francisco.

"Al Jazeera hopes through the attention of the world’s media and partners, pressure can be brought to bear on the Egyptian authorities to hasten the release of Peter Greste, Mohammed Fahmy, Baher Mohamed and Abdullah Al Shamy by reminding them in a united voice, that journalism is not a crime," the media network said in a statement issued on Wednesday.

Award-winning Peter Greste, bureau chief Mohamed Fahmy and producer Baher Mohamed were detained on December 29, taken from a hotel, and were accused of spreading false news, and belonging to a "terrorist group." They stood trial on February 21.

The trial was then adjourned to March 5.

Abdullah Al Shamy from the Arabic broadcaster was detained more than six months ago without any charges and has been on a hunger strike since January 23.

Global concern

Freedom of speech in Egypt has been the focus of mounting global concern since the government adopted a hardline approach towards journalists. The country has been ranked the third deadliest destination for journalists in 2013 by the Committee to Protect Journalists.

Commenting on the Action day, Mostefa Souag, acting General Director of Al Jazeera Media Network said: "We truly appreciate the solidarity from everybody right around the world. The pressure, support and calls for our colleagues to be released have continued to keep the story in the news.

"The Global Day of Action is about the freedom of the press, it is about objective reporting and to ensure journalists cannot be gagged or silenced.

"We ask everyone to contribute to the Global Day of Action on Thursday 27th February. Journalism is not a crime."

An online #FreeAJstaff campaign has had a quarter of a billion hits on twitter alone since the February 1.

To build on that, Al Jazeera will be using Thunderclap to allow people to pledge a Tweet, Facebook post, or Tumblr post containing the same message that will be published at the same time throughout the world.

Institutions including the White House, the European Union and the United Nations have called for the release of the journalists, and for press freedoms to be upheld.