LONDON: Amnesty International called on Iran on Tuesday to free a female journalist who on the weekend started a one-year prison term on charges of "spreading propaganda against the system" and "insulting" President Mahmoud Ahmadinejad.

"The Iranian authorities must immediately and unconditionally release Jila Baniyaghoob, who is a prisoner of conscience held solely for peacefully exercising her rights to freedom of expression and allow her to resume her profession," Amnesty's deputy programme director for the Middle East, Ann Harrison, said in a statement.

Baniyaghoob, 41, worked for a string of now-closed reformist newspapers. The charges against her stemmed from her reporting of the 2009 re-election of Ahmadinejad and of the street protests that ensued.

She was arrested in 2009 along with her journalist husband, who has been in prison ever since on similar charges.

Baniyaghoob was given her prison sentence in 2010 along with a 30-year ban on practising journalism. She was tried and acquitted three times.

In April 2011, authorities added the charge of maintaining a blog "without permission from government authorities," according to Amnesty.

The London-based rights group also appealed to Iran to release other "prisoners of conscience," including journalist-activist Isa Saharkhiz, who it said last week started a hunger strike.

The Amnesty statement followed a call by UN chief Ban Ki-moon to Iran "to release opposition leaders, human rights defenders, journalists and social activists to create the conditions for free expression and open debate."

Ban, who made the appeal in a speech in Tehran on the sidelines of a Non-Aligned Movement summit, said those voices needed to be heard ahead of Iran's 2013 presidential election to choose a successor to Ahmadinejad, who is in his final term.

"Restricting freedom of expression and suppressing social activism will only set back development and plant the seeds of instability," Ban warned.