Bahrain rounded up dissidents on March 17 as it came under mounting diplomatic pressure to end a bloody crackdown on Shiite-led protesters which has alarmed its ally the United States and infuriated Iran.

According to AFP, five hardline Shiite activists and one Sunni were arrested during the night, a parliamentarian from the Shiite opposition alliance said, after a day of violence which left five dead in the Sunni-ruled kingdom.

"They were arrested in the night," Khalil Marzouk, deputy leader of the Al-Wefaq opposition movement, said.

Among those detained was Hassan Mashaima, a leader of the hardline Shiite Haq group which is seeking to overthrow the Sunni monarchy that has ruled the Shiite-majority island state for 230 years.

The government has not confirmed the arrests.