JENSON BUTTON has expressed fears over the safety of the new Baku Street Circuit, and accused Formula One's governing body of going "backwards" ahead of the Azerbaijan Grand Prix.

Button, who with nearly 300 grands prix appearances, is the most experienced driver on the grid, but the Englishman believes the lack of run-off area, at a circuit which is being billed as the fastest in the sport's history, is a major concern.

The run-off area is a safety net for drivers if they make a mistake at high speed, or suffer a mechanical fault such as a tyre blow-out.

"We work so hard on safety, improving circuits all the time, and then we come here and we have corners like turn three, turn seven and turn 14 and they don't have any run-off at all," said Button, the 2009 world champion.

"As far as I know the FIA do every test possible for safety, and the run off-areas that you need for each corner. The way we have gone with safety, pushed it, and some of the issues we have had in the past, you would think they would still do that, but it doesn't look like it from some corners.

"The problem is that you can't move the buildings. It is fine as long as nobody has a failure. We just have to hope that doesn't happen. There might be nothing to worry about, but there are certain corners that you can't change which is worrying."

The temporary facility, on the streets of Azerbaijan's capital city, will see drivers roar past the old city walls and historic buildings in excess of 210mph. At nearly four miles it is now the second longest on the calendar.

And while Button admired the layout of the picturesque track, he also moved to voice his worries over the entry to the pit-lane. The tight chicane is followed by a 100-metre run to the white line before the speed limit begins.

"It is like we have gone backwards in certain areas," Button added. "We trust the FIA, and to be fair they do a fantastic job of keeping us safe and they have improved pretty much every circuit we go to. Hopefully I am wrong."

While championship leader Nico Rosberg also predicted a "massive accident" on the entry to the pit lane as drivers attempt to negotiate the fastest route, as well as criticising the lack of run-off, Lewis Hamilton did not appear fazed.

Hamilton, now within nine points of Mercedes team-mate Rosberg courtesy of back-to-back wins in Monaco and Canada, said: "I looked out my window at turn 16 and I think there is too big a run-off area.

"Monaco does not have hardly any run-off, only at the areas that you really need."