Bahraini authorities arrested 50 on Thursday, released one activist on Friday.

Bahraini authorities on Friday released popular Internet blogger Mahmud al-Yusuf whose arrest drew criticism from the US State Department.

Yusuf was already being sued for libel, while a Bahraini government spokesman said Yusuf was questioned on Thursday but gave no further details on his case.

The United States on Wednesday criticized the arrest and renewed condemnation of violence in the Gulf kingdom.

On the other hand, Bahraini opposition groups said the Manama regime arrested 50 activists on Friday night, just before the next-day massive anti-government protests across the country.

The protests are scheduled to take place after Friday Prayers.

Moreover, the Human Rights Watch accused Bahraini forces on Wednesday of using violence against people that had already received injuries during earlier attacks.

The rights body said it had documented several cases in which the forces had "severely harassed or beaten" patients under medical care in the country's Salmaniya hospital in Manama.

The Bahraini protesters continue to demand the ouster of the 200-year-old-plus monarchy as well as constitutional reforms.

Joined recently by police units and troops from Saudi and the United Arab Emirates, the Bahraini government forces have launched a deadly crackdown on the popular revolution that began to sweep the Persian Gulf island on February 14.

At least 25 people have been killed and about 1,000 others injured during the government-sanctioned crackdowns on peaceful demonstrators.

The Saudi-backed forces have recently been sighted while destroying religious and historical monuments of the Muslim Persian Gulf state.