Hundreds of Bahrainis demonstrated on Sunday after a Shiite opposition call for a week of pro-democracy protests to coincide with the F1 Grand Prix to be hosted by the Gulf state.
Waving red and white Bahraini flags and holding pictures of jailed Shiite activist Abdulhadi al-Khawaja, who is on hunger strike, the protesters called for the ouster of the kingdom's prime minister.
"Leave Khalifa, leave," they chanted as they marched in the Shiite village of Bilad al-Qadim, referring to Prince Khalifa bin Salman Al-Khalifa, in office since 1971.
Sunday's protest was the first in a week of daily demonstrations and sit-ins called by Al-Wefaq, Bahrain's largest Shiite bloc, planned to last through the end of the controversial Grand Prix race scheduled for April 22.
Al-Wefaq said the pro-democracy protests under the banner of "steadfastness and challenge" would take place in Shiite villages on the outskirts of Manama, including one on Tuesday near Bahrain's international airport.
Bahrain, where the majority of the population is Shiite Muslim, is ruled by the Sunni Al-Khalifa dynasty.
Al-Wefaq said there are no plans for protests near the Sakhir circuit where the race will be held.
However, the "Revolution of February 14" youth group, whose members have repeatedly clashed with security forces, has called for "three days of rage" from April 20 to 22 in protest at the decision by motorsport chiefs to go ahead with the race.
Al-Wefaq leader Abdel Jalil Khalil told AFP by telephone the bloc would not try to prevent the event but was organising protests to "take advantage of this week's race to highlight our political and democratic demands."
Foreign journalists have been routinely blocked from entering the tiny island state since the the government cracked down on an uprising in February-March 2011 that killed 35 people, according to an independent probe.
The Grand Prix controversy has once again swung the international media spotlight on the troubled kingdom, an opportunity the opposition says it will use to publicise demands for greater equality and democracy.
Bahrain's cabinet insisted in a statement on Sunday that the decision by Formula 1 to go ahead with the race reflected "confidence in the country's security and stability."
The shooting and wounding of a 15-year-old boy by riot police last week had increased pressure on race organisers and participating teams to boycott the event.
But on Friday, both the sport's governing body, the FIA (Federation Internationale de l'Automobile), and commercial rights holder Bernie Ecclestone announced the race will take place as scheduled.
The US-based watchdog Human Rights Watch condemned the decision, arguing it would be exploited by the ruling dynasty "to obscure the seriousness of the country's human rights situation."
The F1 race in Bahrain was cancelled last year in the wake of the Shiite-led uprising and the brutal government crackdown that followed.
On Saturday, an anti-government demonstration turned violent when police used tear gas and stun grenades to disperse crowds gathering in support of Khawaja as fears over his deteriorating health mount.
"Dozens of youths gathered outside the British embassy (in Manama), carrying signs demanding Khawaja's release," said one witness who identified himself only as Hussein.
Speaking to AFP by phone, Hussein said "young girls sat in the street, rejecting police orders to leave," adding that several people were injured when the protests turned violent.
Witnesses said none of the injured sought medical attention at Manama's hospitals for fear of retaliation by security forces.