Despite concerns the annexation of Crimea by Russia would put October's race in doubt, chiefs have signalled things are all but ready.

The confident declaration by an official from race promoter Omega, reported by Russian news agency Interfax, has also been backed up by reports more spectators will be accommodated for than originally planned.

Promoter Sergey Vorobyov is quoted by Germany's SID as saying that "due to popular demand, we have decided to build another grandstand on one of the most interesting points of the circuit".

Russian Deputy Prime Minister Dmitry Kozak has said construction and installation should be completed by August 10.

The race, the 16th on a 19-race calendar, is due to take place on October 12 at the Sochi International Street Circuit, a 5.8 kilometres track in the shadow of the indoor venues used for the Winter Olympic and Paralympic Games in February and March.

Richard Cregan, who was chief executive of the Abu Dhabi circuit, is now a consultant to Sochi organisers.

The Formula One drivers' championship is currently led by Mercedes' Nico Rosberg of Germany, who holds a 29-point advantage over his British team mate Lewis Hamilton after eight races.