Human rights groups have called for Formula One and its governing body, the FIA, to seek the immediate release of a jailed female activist and blogger ahead of this weekend's Bahrain Grand Prix.
Human Rights Watch (HRW) and the London-based Bahrain Institute for Rights and Democracy (BIRD) were among 15 signatories to a letter sent to International Automobile Federation president Jean Todt.
In it they urged Formula One and the FIA to send a high-level delegation to visit Najah Yusuf, a mother of four now serving a three-year sentence, and jailed reporter Ahmed Humaidan.
It said their prisons were only 20 and 24km away respectively from the Sakhir circuit south of the capital Manama.
The race, round two of the championship sanctioned by the FIA, is the biggest annual sporting event in Bahrain and one that pays tens of millions of dollars in hosting fees to Liberty Media-owned Formula One.
The race has been held since 2004, with the exception of 2011 when it was cancelled due to pro-democracy protests led mainly by Shi'ite Muslims in the Sunni-ruled country.
Yusuf has said she was tortured and sexually assaulted while under arrest and a week after posts against the 2017 race appeared on a Facebook account she co-managed.
Writing on the Guardian website, under the headline "every moment I spend in prison in Bahrain stains the reputation of F1", she accused Bahrain's ruling family of using the race to "whitewash its disregard for human rights."
"During this period, Formula One has consistently ignored the abuses that occur," she added.
The Bahrain authorities have said Yusuf's conviction was unrelated to the grand prix.
"Najah Yusuf's defence did not claim during her trial that her right to free speech had been infringed," they said in a statement this month when the same rights groups wrote to Formula One expressing concern.
"Peaceful protests of any kind are protected by Bahrain’s constitution and do not constitute a crime."
British peer Lord Scriven, who has discussed the situation with Formula One's general counsel Sacha Woodward-Hill, told reporters at the HRW offices that the sport must show it did not operate in a 'moral vacuum'.
He said the meeting with Woodward-Hill left him with some optimism, and Formula One had committed to a full independent investigation into the case, but 'warm words are not enough'.
Scriven said that if Bahrain refused to grant access to Yusuf, that would be grounds to cancel the race.
"Even at this last minute, they have to take decisive actions," he said. "I think this is a litmus test for F1 leadership."
Scriven said that otherwise the rights groups would have to 'turbocharge' the campaign and try to engage the likes of Mercedes' five-times world champion Lewis Hamilton.
"If Sacha Woodward-Hill and the leadership don't show they are serious, then it's down to drivers and sponsors to actually take that moral, ethical and legal step to say 'we will not drive and we will not participate'," he said.