Formula One chiefs have been urged by Labour to cancel this weekend's Bahrain Grand Prix amid continued clashes between police and anti-government protesters.
Shadow foreign secretary Douglas Alexander said that proceeding with the event would "send the wrong signal".
At the start of what is expected to be a week-long run of demonstrations, police and protesters were engaged in a running battle on the outskirts of the Bahraini capital Manama.
Practice for the Grand Prix is scheduled to begin on Friday, with the main race taking place on Sunday.
Mr Alexander told the Press Association: "F1 bosses should call off the scheduled Bahrain Grand Prix.
"To go ahead at present risks sending the wrong signal at a time when the authorities in Bahrain should be focused on delivering real reform."
The latest skirmishes took place in Salmabad, a village six miles from the centre of Manama and 11 miles north of the Bahrain International Circuit (BIC) where the race is due to be held.
The clashes, on the third day of mourning for the death of local cameraman Ahmed Ismael Hassan Al Samadi, were similar to what has regularly taken place in recent months.
A 2,000-strong group including men, women and children marched through the streets calling for the end of the reign of King Hamad, whose minority Sunni government rules over a majority Shia population.
The men then "armed" themselves with Molotov cocktails, threw chunks of concrete on the road where they stood to form a makeshift roadblock, and covered their mouths with bandanas or gas masks in readiness for the tear gas to come.
The Bahraini riot police, who had been waiting behind a nearby university building, were ultimately goaded from their hiding place as the protesters, then numbering around 200, decided to march towards them.
The police responded with tear gas, dispersing their aggressors who also threw stones and bricks, as well as setting alight rubbish bins and small piles of wood in the middle of roads.
There appeared to be no casualties and the gathering was broken up after around 30 minutes.
Bahrain International Circuit chairman Zayed R Alzayani said he did not believe the future of the race was at stake.
He said: "I don't think anything drastic will happen. It's not Syria or Afghanistan. I don't see why anything should happen this year that hasn't happened in the previous years.
"The race will be positive to the country, positive to the economy which has suffered a lot in the last year and a half, and it will put things in perspective.
"A lot of the damage that has happened to Bahrain post the events of last year have been driven by perception, by people not necessarily writing what they see or hear.
"For us, we will be happy for the teams and the journalists and the media to come to Bahrain and see it and then write about it.
"Things are not 100%, but they are not as bad as people make them out to be."
In London, two protesters climbed on to the roof of the Bahraini Embassy on Monday, displaying a banner and waving a flag.
Meanwhile, a leading human rights group said torture and ill-treatment were continuing in the Gulf kingdom.
Amnesty International said it had evidence of people being kept in prison for participating in anti-government protests without using violence.
It found that security forces continue to respond to demonstrations with excessive force, and that a 14-year-old boy and 81-year-old woman died after tear gas was fired into their homes in recent months.
In a report, the charity said the Bahraini authorities were "more concerned with rebuilding their image" than introducing human rights and political reforms.
It concluded that recommendations made by the Bahrain Independent Commission of Inquiry (BICI) in November have been "only partially and superficially" implemented.
Amnesty said investigations into allegations of torture and unlawful killings have been "shrouded in secrecy" and only nine low-ranking policemen have been put on trial.
Amnesty International's Middle East and north Africa deputy director Hassiba Hadj Sahraoui said: "With the world's eyes on Bahrain as it prepares to host the grand prix, no one should be under any illusions that the country's human rights crisis is over.
"The authorities are trying to portray the country as being on the road to reform, but we continue to receive reports of torture and use of unnecessary and excessive force against protests. Their reforms have only scratched the surface.
"The government's huge financial investment in international experts to help them reform will go to waste unless it shows real political will to take difficult decisions, in particular holding to account senior members of the security forces accused of violations, releasing prisoners of conscience and addressing the underlying discrimination against the Shia majority population.
"The establishment of the BICI was a real breakthrough and raised expectations that things would be different in Bahrain. It is time for the Bahraini government to match its public pronouncements with genuine actions."
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