Last updated on .From the section Formula 1

Follow the Chinese Grand Prix on the BBC Sport website and BBC Radio 5 live

Chinese Grand Prix on the BBC Dates: 7-9 Apr Venue: Shanghai International Circuit Coverage: Practice and qualifying on BBC Radio 5 live sports extra; race on BBC Radio 5 live. Live text commentary, leaderboard and imagery on BBC Sport website and app.

Formula 1 was forced to call off second practice at the Chinese Grand Prix because poor visibility prevented the medical helicopter operating.

Low cloud, rain and smog in Shanghai meant the helicopter was unable to land at the designated hospital.

Safety requirements dictate cars cannot run if the helicopter cannot fly.

The conditions also affected first practice, in which Red Bull's Max Verstappen was fastest during 10 minutes of running on a damp track.

The Dutchman, who was 1.5 seconds quicker than anyone else, said: "The car felt pretty good. Difficult to say [where we are] because Mercedes and Ferrari haven't run so we don't know their pace.

"But from our side it felt good and from the driver's side if the feeling is OK the speed is normally pretty good."

Valtteri Bottas was the only driver of the top two teams to set a lap time all day. The Finn was ninth quickest.

Team-mate Lewis Hamilton and Ferrari drivers Sebastian Vettel and Kimi Raikkonen managed only a total of five laps between them.

Drivers were confined to the garages as FP2 turned into a waiting game

Lewis Hamilton crossed the track to throw team caps to fans

As the clock ticked down, Hamilton did his best to entertain the crowd by crossing the track opposite the pits and walking in front of the main grandstand, filming for his social media accounts and signing caps which he then threw to the fans.

The forecast is better for Saturday, with dry weather predicted and occasional sunshine, and temperatures of 20C.

However, rain is due to return for race day on Sunday, with heavy downpours predicted overnight on Saturday and then fading through the morning, and temperatures of only 13-15C.

If conditions on Sunday are similar to those on Friday, the race would have to be delayed until organisers could guarantee a suitable medical evacuation method.

Red Bull's Max Verstappen was fastest in first practice, which was also interrupted twice by the same issue

Chinese Grand Prix practice results in full