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(CNN) -- The continuing unrest in Bahrain which left three people dead on Thursday also forced the cancellation of a Formula One feeder series event, raising further doubts that the elite motorsport's new season can begin in the trouble-hit kingdom next month.

F1 teams are due on the island for testing sessions from March 3-6 ahead of the opening race the following weekend but the sport's rights-owner Bernie Ecclestone admitted it could be axed if the civil unrest continues.

"If it's not quietened down by Wednesday, I think we will have to cancel probably," he was quoted as saying by reuters.com. Ecclestone also revealed he was in contact with Bahrain's Crown Prince for updates on the situation.

Preparations for the two GP2 Asia Series races to be held at the Sakhir International Circuit on Friday and Saturday were halted when Thursday's track activity was first called off and then the whole event postponed.

"At the request of the Bahrain Motorsport Federation, it has been decided that the remainder of the meeting which was supposed to take place this week at Bahrain International Circuit is canceled due to force majeure," GP2 organizers said in a statement.

Thursday's practice session had earlier been postponed as the event's medical staff were called to Manama's hospitals in case of an emergency.

Three die as Police move on protesters in Bahrain

Will Buxton, a motorsport journalist covering the event for the SPEED channel, had raised concerns about whether the races would go ahead.

"If the medical crews aren't available today, will they be tomorrow or Saturday? Let's cut our losses and get the hell out of here," he wrote on social networking website Twitter before safely returning to his hotel in the capital Manama.

He said there were reports that Abu Dhabi might take over the F1 testing session and race.

Buxton earlier said of the situation while at Sakhir: "We've been watching CNN in the media center all morning. The channel just went dead. Hearing that some GP2 teams are staying near Pearl Roundabout and have been told not to go back to their hotels."

The iconic roundabout, in Manama's financial district, has been the center of the protests.

Sakhir, which in 2004 became the first Middle Eastern circuit to stage an F1 race, is about 30 kilometers (18.5 miles) south of the capital.

If the F1 race is called off, it would be a big blow to Bahrain's economy -- the 2008 event was worth $600 million in direct and indirect revenue, according to the Marcopolis website. The Gulf Daily News reported that the first three races brought in a combined income of $658 million.

British newspaper The Times reported that it cost Bahrain race organizers $40 million to secure a place in this year's calendar, plus another $20 million to ensure it was the first of the season.

The $200 million Sakhir circuit has also had a $50 million revamp since last year's race, according to The Times.

Ecclestone had already voiced concerns about the situation before he admitted the event could be called off.

"The danger is obvious, isn't it? If these people wanted to make a fuss and get worldwide recognition, it would be easy, wouldn't it?" the 80-year-old told Britain's Daily Telegraph on Wednesday.

"You start making a problem on the start grid in Bahrain and it would get worldwide coverage."

Race organizers earlier issued a statement saying they "are monitoring the situation very closely ... and will respond appropriately to any further developments."

The unrest in Bahrain follows the pattern of Tunisia and Egypt, where civil protests have led to the resignations of each country's president.

The Bahrainis are seeking to end the 30-year rule of Prime Minister Sheikh Khalifa bin Salman al-Khalifa.

Bahrain first hosted a grand prix in 2004 and has been the season-opener of the Formula One circuit since 2006.