Motorsport: Turkish Grand Prix organisers have doubled the security measures for Sunday's Formula One race after last month's London suicide bombings. "We doubled it after the British Grand Prix, or rather what happened that week," Turkish Autosport Federation president Mumtaz Tahincioglu said in Istanbul yesterday.

He said 4,000 unarmed private security guards would protect the circuit on the Asian side of Istanbul along with 2,000 paramilitary Jandarma police and 800 city police. Plain-clothes police officers will also mingle with the crowds attending the first grand prix held in the country.

Armed police protected the access roads to the circuit yesterday, though there was no action on the track, with sniffer dogs in the paddock as team staff arrived in the morning. Tahincioglu said there had been no specific threats to the event. The Turkish federation had its own people at Silverstone last month "watching and getting information" but the British police had not been involved.

BAR's Jenson Button, the only English driver in Sunday's race, said he had no concerns. "There's a lot of places in the world where the security isn't fantastic. I think here you are in a place where they know the security has to be good."

The new circuit could prove a thriller ride, drivers said after initial inspections yesterday.

"I think there will be some good overtaking moves here," said Button. "It looks like a very exciting circuit, you've got so many blind corners that keep the adrenaline pumping."

Renault's championship leader Fernando Alonso, 26 points clear of McLaren's Kimi Raikkonen with six races remaining, also sounded pleased.

"I think the same as everyone, quite impressed about the circuit. The track is a little bit different compared to all the new circuits we have seen in the last three or four years, Bahrain or China."

The undulating, anti-clockwise circuit on the Asian side of Istanbul has 14 turns with changes of gradient and blind crests to test the drivers' mettle.

Meanwhile, Sauber's Jacques Villeneuve is so confident he will be with BMW next season he is not talking to any other team about a drive. "I'm not the kind of guy to go talk to everyone if I already have something in my hands," he said yesterday.

Villeneuve's future has been called into question this season, owing to a slow start to the year, despite the 34-year-old having a year to run on his contract.