DUBAI (Reuters) - Bahrain released a prominent blogger but detained several other people, including a pro-opposition doctor, the latest in a series of arrests since a crackdown on protests, opposition sources said on Friday.
The tiny island kingdom's Sunni rulers have stepped up arrests of cyber activists and Shi'ites, with more than 300 detained and dozens missing since security forces broke up pro-democracy street protests earlier this month.
It imposed martial law and called in troops from fellow Sunni-ruled neighbors, including Saudi Arabia, to quell the protest movement led mostly by the state's Shi'ite majority.
More than 60 percent of Bahrainis are Shi'ites and most want a constitutional monarchy.
Mattar Ibrahim Mattar, a member of Bahrain's largest Shi'ite opposition group, Wefaq, said the party's official arrest count was 329 by Thursday, but that the real number was likely to be more than 400.
He said at least 20 people had been detained on Thursday and 31 were missing. It was unclear if those people were in hiding or had been abducted.
There have been several reports of missing people who have turned up dead days later, but activists say that many of their peers are also going into hiding to avoid arrest.
The severity of Bahrain's crackdown, in which public gatherings are banned and security forces have been deployed at checkpoints, stunned Bahrain's Shi'ites and angered the region's non-Arab Shi'ite power, Iran.
Saudi Arabia and other Gulf Arab states, fearful of rising Iranian influence, see Bahrain as the biggest threat of all the popular uprisings that have swept the region since January.
"We demand the withdrawal of foreign troops, which entered Bahrain under the pretext of protecting Bahrain from external threat, and we call on those who have committed crimes against the people of Bahrain to be held accountable," Iraqi MP Ahmed al-Chalabi said at a news conference in Baghdad.
"The problem in Bahrain may be a fuse to a large explosion in the whole region," he said.
Prominent Bahrain blogger Mahmood al-Yousif, who for years has promoted anti-sectarianism under the slogan "No Shi'ite, No Sunni, Just Bahraini," was detained on Wednesday and released late on Thursday.
"I'm back home now with my family. Everything is fine," he told Reuters by telephone. "I've been treated well enough. They investigated me but didn't find anything," he said.
Opposition sources said Abdul Khaleq Al Oraibi, a doctor at Salmaniya Hospital, Bahrain's biggest, had also been detained.
Oraibi, who once considered running as a member of parliament for Wefaq, had been publicly critical of the lack of access for medics to wounded protesters.
(Additional reporting by Muhanad Mohammed in Baghdad; Writing by Erika Solomon and Nick Macfie; Editing by Louise Ireland)