Hundreds, possibly thousands, of people are believed to have been killed
in the army's crackdown on the mass demonstrations.
Many veterans of the movement who were not exiled continue to suffer government harassment.
Zhou had been living in the United States since smuggling himself out of
China in 1993, but was arrested in August 2008 while attempting to enter Hong
Kong on a fake Malaysian passport bearing the name Wang Xingxiang.
Money transfer case
Supporters said he was planning on returning to mainland China to visit his elderly parents and accused Hong Kong's government of violating its own laws in sending him to the mainland.
Hong Kong was handed back to China in 1997 but maintains its British colonial-era legal system and does not have deportation and removal treaty with mainland China.
Chen said the case stems from a complaint by Hong Kong's Hang Seng bank about a suspicious request for the transfer of funds out of an account registered to Wang Xingxiang - the name in Zhou's fake passport.
The signature on the transfer form did not match that of the original account holder and the name Wang Xingxiang was placed on a money laundering watch list, according to Chen.
He said the amount of the attempted fraud was listed as $773,000, but declined to give other details of the case.
Zhou denied the fraud charge, saying he was the victim of bad luck and mistaken identity.
He said he obtained the fake passport through an immigration agency, a common practice among Chinese exiles who often find themselves stateless after Beijing refuses to renew their passports.
Hong Kong's government has refused to comment on Zhou's case.