Ghoncheh Ghavami, the British-Iranian woman sentenced to one year in jail for protesting outside of an Iranian-Italian volleyball match, started her second hunger strike on Tuesday, BBC's Arabic news website reported.
Ghavami's mother, Suzan Moshtaghian, told BBC that her daughter "declared her hunger strike to protest [her] illegal imprisonment."
Meanwhile, Ghavami's lawyer said he saw documents confirming the one-year verdict, "but the attorney general has not yet confirmed the court decision."
The mother said the judgment was delivered with no incriminating evidence.
Earlier in October Ghavami announced her hunger strike, which lasted for two weeks, as she denounced being put in a solitary confinement, BBC said.
The 25-year old Ghavami, who graduated from a law school in London, was arrested in June outside Azadi Stadium in Tehran as part of a demonstration calling for women's rights to attend matches, as they were trying to watch a men's volleyball match between Iran and Italy.
Soon after her arrest she was released for a few days, and rearrested again, and since then Ghavami has been held in a Tehran prison.
In 2012 Iran banned women from attending volleyball matches, along with football, BBC said.
"We cannot let women attend matches in the stadiums, and police are applying the law," General Ismail Ahmdi, Iran's internal security chief, told Iranian FARS news agency earlier in June. Ahmdi added that "mixed crowds in stadiums are not for the public interest."
Ghavami is a dual-national, but Iran doesn't recognise second nationalities within its borders.
UK's Foreign Ministry has announced its concern towards Ghavami's detention, but according to international law, no country can provide official diplomatic protection for a citizen in another homeland.