Hundreds of F1 engineers, mechanics and catering staff have been issued with two return tickets from Sunday's grand prix in China: one for Bahrain and one for Europe and home in case the race was cancelled, The Times said, without quoting sources.
One unnamed member of the 12 Formula One team principals separately told The Guardian that he believed the race in the Gulf state on April 22 should be either cancelled or postponed.
"I feel very uncomfortable about going to Bahrain," the principal was quoted as saying.
"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.
"But I don't see any other way they can do it."
The source, who claimed his views were representative of the other principals, said that they all hoped that the race is called off, even though they were cleared to go by insurers and from government advice.
The team principal said that like his colleagues, he was concerned about the threat of violent demonstrations and had ensured that all his employees were covered for acts of terrorism and civil disorder before, during and after the GP.
The Bahrain Grand Prix was called off in 2011 due to the unrest that gripped the Shiite-majority state after a mid-March crackdown on protests demanding democratic reforms that would challenge the power of the Sunni Al-Khalifa ruling dynasty.
According to an independent probe, 35 people were killed in the unrest between mid-February and mid-March 2011.
There are also fears about violence if jailed activist Abdulhadi al-Khawaja dies in custody.
Khawaja, a Shiite who was condemned with other opposition activists to life in jail over an alleged plot to topple the Sunni monarchy during a month-long protest a year ago, began a hunger strike on the night of February 8-9.
Formula One supremo Bernie Ecclestone has insisted that a outbreak of fresh violence will not affect this year's race and motor racing chiefs said they were in "daily contact with the highest authorities" in Bahrain.
The local authorities there had assured them that "all the security challenges are under control", the international motor racing federation the FIA said last week.
But the crackdown on demonstrations has continued, prompting Shiite activists to demand the race be scrapped.
The chairman of the Bahrain International Circuit, Zayed R. Alzayani, said that holding the grand prix was essential to help the country move on, saying it was "not right" to deprive motorsports fans of the chance to see the race.
"I don't know why we are being dragged into the politics of the event. We are a social event, we are a sports event and we would like it to stay that way," he told BBC radio in an interview on Monday.