Al-Jazeera vowed Monday "not to leave" Egyptian producer Baher Mohamed in jail following the release of Australian journalist Peter Greste and amid rising hopes Canadian Mohamed Fahmy will soon be deported.
All three were jailed on New Year's Day in 2014, for allegedly aiding the blacklisted Muslim Brotherhood group.
Greste, an award-winning reporter, was deported from Cairo on Sunday after 400 days in captivity and flew to Cyprus.
And Canadian officials have said they are "very hopeful" that a deal can be struck for Fahmy "shortly", with both reporters being deported under a decree passed by Egypt's President Abdel Fattah al-Sisi that allows for the transfer of foreigners on trial.
But there are concerns that no such escape route exists for Mohamed, an Egyptian, who until Sunday shared a cell with Greste in Cairo's Tora prison.
Heather Allan, head of newsgathering at Al-Jazeera English, said the pan-Arab television network would fight to free all three.
"We are very worried about him (Baher Mohamed)," admitted Allan. "I think it is not lost on anybody that there is an Egyptian national involved here."
Asked if Al-Jazeera was hopeful he may be released along with his colleagues, Allan added: "I can't say I am confident, no. I just don't know, honestly. Are we going to keep on fighting it? Absolutely -- we are not going to leave him there."
She said Mohamed "must be feeling pretty isolated at the moment", but the Qatar-based broadcaster was in constant touch with the producer's family.
"We might have to try some other tactics because we don't have a foreign country involved, but our commitment to getting him out is just as strong as it ever was."
- 'Last to find out' -
The arrest of the three journalists two years ago sparked worldwide condemnation, with Washington and the United Nations leading calls for their release.
They were arrested at the height of a diplomatic row between Egypt and Qatar, which owns Al-Jazeera.
The broadcaster had been critical of the deadly crackdown on Mohamed Morsi's Muslim Brotherhood movement following the Islamist leader's overthrow.
Qatar has since moved to mend ties with Egypt, and Al-Jazeera has closed its Arabic-language Egyptian affiliate which backed the Brotherhood.
Allan added that she was hopeful Fahmy would be released, though Al-Jazeera "might be the last to find out".
She said the first it knew about Greste's release was when he phoned the station from the departure lounge at Cairo airport.
Greste, 49, was in good health, she said, but would be allowed to rest for as long as he wants in Cyprus.
"We have said to him 'Look, whatever you want to do, do it.'
"He has got a story to tell but we are going to have to give him time to decompress, and we are standing by to help him in any way he that needs help."
Greste's family held a news conference in Brisbane on Monday calling for the release of his two colleagues.