DUBAI (Reuters) - Bahraini opposition activists said they blocked roads with burning tyres on Thursday to demand the release of women prisoners, many of them locked up during more than a year of protests against the island kingdom's rulers.
Bahrain's interior ministry blamed "vandals" for the road blockages which stopped traffic in the capital Manama.
"Legal measures were taken and the situation was returned to normal," the ministry said in a statement on Twitter, without going into further detail.
The government this week announced stiffer measures against illegal protests, but demonstrations have continued.
Activists from the "February 14 Youth Coalition" - a group opposed to the monarchy - posted videos online showing masked youths placing tyres in several areas of Manama and setting them alight.
A statement published with the video said they were calling for "the immediate release of women prisoners in the regime's prisons".
Zainab al-Khawaja, daughter of a jailed protest leader who is on hunger strike, was detained as she tried to protest on a highway during Bahrain's Formula One Grand Prix last month, activists said.
Three other women were arrested two weeks ago after staging a protest outside a prison for the release of Khawaja's father, campaigners added.
The opposition party Wefaq says at least 700 people are in jail pending trial or serving terms. The police have not given a figure for the total held.
Bahrain has been in turmoil since pro-democracy protests erupted last year, partly inspired by successful revolts in Egypt and Tunisia.
The ruling Al Khalifa monarchy has rejected calls for an elected government and parliament with full legislative powers, dubbing the opposition as lackeys of Iran.
Leading activist Nabeel Rajab was arrested last week for questioning over accusations he was using Twitter messages to incite riots. He has been charged for organizing illegal protests.
"Rajab is a prisoner of conscience being held solely for expressing his views," Amnesty international said in a statement demanding his release.
The government also warned clerics not to incite protests or insult state institutions incitement in sermons and insulting state institutions, widely taken as a threat against leading cleric Sheikh Isa Qassim.
The government prevented Wefaq staging a march in Manama on Wednesday.
The United States, whose Fifth Fleet is based in Manama, has been muted in its criticism of Bahrain since the uprising began. It has called for restraint from both the opposition and the government.
Crown Prince Salman thanked U.S. Secretary of State Hillary Clinton in Washington on Wednesday for U.S. support during the crisis, the state news agency BNA said.
(Reporting and writing by Andrew Hammond; Editing by Sami Aboudi and Andrew Heavens)