Formula One looks set to come under fresh pressure to shelve Bahrain's grand prix this week in China, where preparations have been rocked by ongoing protests and a hunger strike in the desert state.
As teams and officials gather at Shanghai International Circuit, the focus is on events thousands of miles (kilometres) away in Bahrain, where activists have called for "three days of anger" during the April 20-22 race.
Last year's Bahrain race was postponed and eventually called off after violent anti-government demonstrations and a deadly crackdown, and team officials have again voiced disquiet, according to British media.
Formula One supremo Bernie Ecclestone admitted he could not force teams to take part -- but he said only officials in Bahrain could decide whether the race would go ahead.
"We've no way we can force people to go there," Ecclestone said. "We can't say, 'You've got to go' -- although they would be in breach of their agreement with us if they didn't go, but it doesn't help.
"Commercially, they have to go, but whether they decide to or not is up to them. I've had no one say anything other than, 'We're going to be racing in Bahrain'."
Teams are certain to face questions about Bahrain in Shanghai. This week, seven police were wounded in a blast and Denmark's prime minister said jailed activist Abdel Hadi al-Khawaja was in a "very critical" condition after two months on hunger-strike.
A youth group allied to Bahrain's Shiite opposition called for protests during the race and also launched a campaign on Twitter to stop it from going ahead.
"I feel very uncomfortable about going to Bahrain," an unnamed principal was quoted as saying by The Guardian.
"If I'm brutally frank, the only way they can pull this race off without incident is to have a complete military lock-down there. And I think that would be unacceptable, both for Formula One and for Bahrain."
The Times, without quoting sources, reported that teams had made contingency plans by issuing staff with two return tickets from China: one via Bahrain, and one directly back to Europe.
But Zayed al-Zayani, chairman of the Bahrain International Circuit, blasted "armchair observers" for "scaremongering" and creating "huge misconceptions about the current situation".
Motorsports governing body the FIA last week said it was monitoring the situation daily and had been assured that "all the security challenges are under control".
Speaking at last month's Malaysian Grand Prix, reigning world champion Sebastian Vettel and Michael Schumacher both said they were comfortable about racing in Bahrain.
"If they decide it's safe we shouldn't worry. I'm happy to go (to) Bahrain," Vettel said, while Schumacher described himself as "pretty relaxed" about the situation.
The controversy has stolen the spotlight from what is shaping as a gripping season, with McLaren's Jenson Button winning the first race in Australia and Ferrari's Fernando Alonso the surprise victor in rain-hit Malaysia.
McLaren's Lewis Hamilton will look to repeat last year's win on Shanghai's high-speed straights, after finishing third twice despite two pole positions in a car which looks to have the beating of Vettel's Red Bull.
"I won't deny that I'm disappointed to have had two pole positions and not to have been able to convert either of them into victories," said Hamilton, the 2008 world champion.
"But I prefer to think of it that luck just hasn't been on my side, and that it will swing my way sooner or later," added the 27-year-old.
Alonso masterfully steered his cumbersome, work-in-progress Ferrari to victory in storm-interrupted Malaysia, and attention will also fix on Sergio Perez, 22, who against all odds finished second for Sauber at Sepang.
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