F1 bosses have a “contingency plan” and issued warnings to cope with poor air quality at the Singapore Grand Prix.

A dense cloud of haze has descended on the city following forest fires in neighbouring Indonesia.

It has prompted Singapore’s National Environment Agency to warn people to “reduce prolonged or strenuous outdoor physical exertion”.

“Race organisers have taken measures to reduce the impact of the haze for the race weekend,” an F1 spokesperson said.

“They have put in place a number of measures, including public information at the circuit.”

The night race at the Marina Bay Street Circuit is also known for being physically demanding due to its humidity.

Singapore race officials say the air quality situation is “highly changeable” meaning it is “not possible” to reliably predict the PSI – Pollutant Standards Index – level for the race weekend but that they will “monitor it closely” with the race is scheduled to go ahead as planned.

British driver Lewis Hamilton leads the championship by 63 points heading into the weekend, with seven races of the season remaining.

The five-time world champion has won in Singapore in the past two seasons.