Youth Demand demonstrators have thrown red powder paint on Tower Bridge during the London Marathon.

The group, which is calling for a trade embargo on Israel, said two of its supporters jumped over the barriers and threw the substance in front of the men’s elite race at around 10.35am.

An image shared by Youth Demand shows two people standing in the middle of the road wearing T-shirts emblazoned with the message: “Youth Demand: Stop Arming Israel”.

The two protesters are in custody after being arrested on suspicion of causing a public nuisance, the Metropolitan Police said.

A statement said: “At around 10.38am, two protesters from Youth Demand jumped over barriers at Tower Bridge and threw red paint onto the road.

“Marathon event staff intervened to remove the protesters from the path of the men’s elite race which was able to pass unobstructed. He was quickly supported by police officers who arrested the protesters on suspicion of causing a public nuisance. They remain in custody.

“The paint appears to be chalk-based and is not expected to present a hazard to runners yet to pass this point.”