Formula 1's governing body is looking into a dangerous incident that occurred during the Singapore Grand Prix.

Recalling a similar incident at the night race in 2015, a marshal retrieving debris had to sprint to safety on Sunday as the racing pack approached after the safety car period.

"At least the guy last year was drunk," Mercedes team boss Toto Wolff joked, according to Bild.

"That was pretty hairy," said Nico Rosberg. "I think just as we didn't expect the restart, he didn't either, because the restart was pretty abrupt."

Germany's Auto Motor und Sport said that even race director Charlie Whiting was caught by surprise.

"Suddenly I saw yellow flags again," he is quoted as saying. "At the restart they should all be green."

Whiting confirmed that the current safety protocol at the end of a safety car period is to ask the clerk of the course if the track is clear not once, but three times.

"Then we order the safety car in. We were surprised that a marshal was then suddenly on the track," he said.

Auto Motor und Sport reports that the FIA is now awaiting a report about the race from Gabriel Tan, the local clerk of the course.

Germany's Auto Bild says that the marshal was cleared to enter the track by his local boss.

"It was very dangerous," said Wolff. "But we have to defend the work of the race organisers - they restarted the race very quickly, which is what we ask for.

"A marshal who only meant well and wanted to clear the track was obviously surprised. Luckily, no-one was hurt."

The season continues next weekend in Malaysia.