Iran's imprisoned Nobel Peace Prize laureate, Narges Mohammadi, has been sentenced to another year in prison over her activism, her lawyer said on Wednesday.

Mostafa Nili, Mohammadi's lawyer, told The Associated Press that his client was convicted on a charge of making propaganda against the system. Nili said the sentence came after Mohammadi urged voters to boycott Iran's recent parliamentary election, sent letters to lawmakers in Europe and made comments regarding torture and sexual assault suffered by another Iranian journalist and political activist.

Mohammadi is being held at Iran's notorious Evin Prison, which houses political prisoners and those with Western ties. She already had been serving a 30-month sentence, to which 15 more months were added in January. Iran's government has not acknowledged her additional sentencing.

The latest verdict reflects the Iranian theocracy's anger that she was awarded the Nobel prize last October for years of activism despite a decadeslong government campaign targeting her.

Mohammadi is the 19th woman to win the Nobel Peace Prize and the second Iranian woman after human rights activist Shirin Ebadi in 2003. Mohammadi, 52, has kept up her activism despite numerous arrests by Iranian authorities and years behind bars.

In November, Mohammadi went on a hunger strike over being blocked along with other inmates from getting medical care and to protest the country's mandatory headscarves for women.

Mohammadi was a leading light for nationwide, women-led protests sparked by the death last year of a 22-year-old woman in police custody that have grown into one of the most intense challenges to Iran's theocratic government. That woman, Mahsa Amini, had been detained for allegedly not wearing her headscarf to the liking of authorities.

For observant Muslim women, the head covering is a sign of piety before God and modesty in front of men outside their families. In Iran, the hijab — and the all-encompassing black chador worn by some — has long been a political symbol as well, particularly after becoming mandatory in the years following the 1979 Islamic Revolution.

While women in Iran hold jobs, academic positions and even government appointments, their lives are tightly controlled, in part by laws like the mandatory hijab. Iran and neighbouring Taliban-ruled Afghanistan are the only countries to mandate the headscarves. Since Amini's death, however, more women are choosing not to wear hijab despite an increasing campaign by authorities targeting them and businesses serving them.