Australian journalist Peter Greste has been behind bars since December 29, 2013, along with Canadian-Egyptian Mohamed Fahmy and Egyptian Baher Mohamed in a case that sparked a global outcry.
Greste and Fahmy were sentenced to seven years and Mohamed was jailed for 10 years on charges of defaming Egypt and aiding banned Islamists, prompting claims their trial was politically motivated -- and demands for a presidential pardon.
Australia has played down hopes Greste could be freed ahead of an appeal this week.
Three other foreign journalists, including British television reporter Sue Turton and Dutch journalist Rena Natjes, were sentenced to 10 years in absentia.
In London, around 50 demonstrators gathered outside the Egyptian embassy, holding placards reading "Free them now" and "Journalism is not a crime".
Many stood with manacled wrists or tape over their mouths.
"The message is 'enough is enough.' Our guys have now been in prison for 365 days," Turton said.
She said the journalists were jailed because the Egyptian government was trying to "send a message" to Qatar, which had backed the Muslim Brotherhood.
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"For Egypt's sake, their economy is not looking too healthy, the tourism industry is flat-lining, so if they release our guys the image of Egypt will improve significantly."
Ann Marcus, Egypt country coordinator for the human rights group Amnesty International, who was at the demonstration, called the reporters' trial "farcical".
There was also a small gathering outside the Egyptian embassy in The Hague, where Natjes read out a letter from Fahmy.
In Australia, Foreign Minister Julie Bishop downplayed hopes that Greste will be released before a January 1 appeal.
She said there had been mixed signals from Egyptian authorities, adding that Foreign Minister Sameh Shoukry had warned her not to expect any developments before this week's appeal.
"We're doing what we can to bring Peter Greste home as soon as possible and I remain hopeful that we can get that message through to the Egyptian government," Bishop told the Australian Broadcasting Corporation.
In a letter to his supporters last week, Greste said he felt proud at what had been achieved so far in stirring political debate about the right to a free press and the persecution of journalists in Egypt.
"We have galvanised an incredible coalition of political, diplomatic and media figures, as well as a vast army of social media supporters for that most basic of rights -- the right to know," Greste said.
Egyptian President Abdel Fattah al-Sisi said earlier this year he could not consider a plea of clemency or a pardon until all legal proceedings have been concluded, including an appeal.