* TV network is based in Qatar, which supported Brotherhood
* Jazeera Cairo office closed hours after Mursi's overthrow
CAIRO, Jan 17 (Reuters) - An Egyptian cameraman arrested this week filming for the Associated Press (AP) was released on Friday, the news agency said, adding that authorities appeared to have mistaken him for an employee of Al Jazeera television.
AP said Hassan Abdullah Hassan was arrested on Wednesday as he filmed outside a polling station during the national referendum on a new constitution.
He said authorities had thought he was an employee of Al Jazeera after his footage was shown on an Egyptian affiliate of the network, according to AP, whose footage is available to any broadcasters who are the company's clients.
This week's referendum is part of an army-backed transition plan that could see General Abdel Fattah al-Sisi, who toppled Islamist President Mohamed Mursi in July after protests against him, run for president.
Egypt accuses Qatar and Qatar-based media network Al Jazeera of backing Mursi's Muslim Brotherhood, which it declared a terrorist organisation on Dec. 25. Authorities have killed hundreds of Brotherhood supporters and arrested thousands since July.
Qatar was a strong financial backer of the Brotherhood's rule and its relationship with Cairo has deteriorated in recent months as it opposes the army's overthrow of Mursi.
The Cairo offices of Al Jazeera have been closed since July 3 when they were raided by security forces hours after Mursi's overthrow.
AL JAZEERA ARRESTS
Egyptian authorities arrested several journalists working for the Al Jazeera network in late December. They remain in detention, judicial sources said.
The general prosecutor's office on Thursday reiterated accusations against the journalists, including broadcasting without a proper licence and with the aim of "touching on" Egypt's national security.
It said some of them had confessed to belonging to "the terrorist group", seemingly referring to the Brotherhood, which the government declared a "terrorist organisation" on Dec. 25. The group says it is committed to peaceful activism.
The statement added that the general prosecutor took into consideration the role of the press in forming public opinion through freedom of expression and that his office was not affected by disputes between political factions.
Al Jazeera said the prosecutor's accusations "do not stand up to scrutiny" and that "claims that anyone has 'confessed' are rejected by our journalists and legal team".
The New-York based Committee to Protect Journalists (CPJ) has urged the Egyptian government to release all journalists.
"Egyptian security forces have been given free rein to target anyone deemed by the government to be sympathetic to the Muslim Brotherhood or who work for outlets in countries that criticised Mursi's ouster," CPJ said this week.
AP said freelance cameraman Hassan's case remained open. "We are pleased that Mr. Hassan has been released on bail, and we hope that any remaining legal questions can be resolved quickly," said John Daniszewski, AP senior managing editor for international news. (Reporting by Shadia Nasralla; editing by Andrew Roche)