Neda Agha-Soltan was shot in the chest
The family of a young woman shot dead at a protest following Iran's disputed presidential election has accused the security forces of killing her.
It is the most strongly-worded statement the family of Neda Agha Soltan have made since her death.
The family's accusation follows the spread of an Iranian government-proposed theory blaming a conspiracy of western governments for the killing.
Ms Soltan was filmed as she lay dying and the video uploaded to the internet.
Her death became iconic in the protesters' struggle against what they said was the fraudulent election of President Mahmoud Ahmadinejad.
"I openly declare that no one, apart from the government, killed Neda. Her killer can only be from the government," Ali Agha Soltan told the BBC's Persian service by telephone from Iran.
The Iranian authorities say foreign governments and the opposition killed her in an attempt to smear the authorities.
On Wednesday government supporters held a demonstration outside the British embassy in Tehran, calling for the a young medical student who tried to treat Ms Soltan as she lay dying in the street to be returned to Iran and even accused him of killing her.
But Mr Soltan dismissed accusations by the authorities that foreign powers and the opposition were involved.
"They've been avoiding responsibility from the very beginning. They want to put the responsibility on other people... This is how the Islamic Republic behaves," he said.
He said that he and his wife were beaten up and detained by the security forces last month when they tried to take part in an opposition demonstration.
Mr Soltan also denied recent reports in an Iranian newspaper that the couple were paid by an American television network, which wanted to make a film about their daughter.
Last month Iran denounced a college at Britain's Oxford University which set up a scholarship in honour of Ms Soltan.