At least 120 protesters were injured in the western Yemen city of Hudeida when security forces and government loyalists used force to disperse a demonstration on Wednesday.
Security forces used live ammunition, batons and tear gas to break up the protest, which demanded the ouster of President Ali Abdullah Saleh.
Government supporters in civilian clothes also attacked the demonstrators in the Red Sea port city.
Yemen's interior minister, Mutahar Rashad Al-Masri, sacked security directors of the provinces of Aden, Taiz and Dhali Tuesday, after the violence used against protesters in those areas.
Yemen's endowments minister, Hamoud al-Hattar, and five governors have been dismissed since massive anti-government demonstrations began early this year.
The Centre of Training and Protection for Journalists' Freedoms in Yemen condemned attacks on journalists in the country, and held Saleh's government responsible for them.
International as well as Yemeni journalists were being attacked and intimidated by security forces in the country, the Centre said in a report issued earlier this week.
Encouraged by anti-government protests sweeping the region, Yemenis around the country have taken to the streets for over a month to demand an end to Saleh's 32-year rule.