Reporters Without Borders (RWB), the Paris-based media advocacy group, has reported that Shiva Nazar Ahari and Jila Bani Yaghoob were arrested earlier this month and began serving jail sentences previously imposed by revolutionary courts.

According to RWB, their arrests bring to five the number of women journalists detained in Iran.

Ahari, a 27-year-old human rights activist and editor of the Azad Zan (Freed Women) website, was sentenced on 28 January 2011 to four years in prison and 74 lashes after being found guilty of plotting against national security and disseminating anti-government propaganda.

Ahari was previously imprisoned for five months on June 14, 2009, following Iran's disputed presidential election, and was jailed again for a 9-month term in December 2009.

Yaghoob, who has worked as a journalist since 1994 writing for several reformist newspapers, was arrested and sent to Evin prison to being serving a one-year sentence. Yaghoob has been harassed repeatedly because of her reporting on sensitive issues, including political protests and the treament of women in Iran.

In 2009, she won the International Women's Media Foundations's "Courage in Journalism Award."

The Islamic Republic of Iran is among the world's most repressive countries for journalists, its media consistently receiving a score of "not free" from the US-based human rights watchdog, Freedom House.

RWB reports that Iran holds the world record for imprisoning women journalists and bloggers, at least 57 of whom have been arrested and given jail terms since the June 2009 election.