UEFA is expected to launch an investigation into the trouble that marred West Ham’s Europa Conference League semi-final victory at AZ Alkmaar, with Dutch police saying there have been no arrests yet.

Pablo Fornals’ injury-time winner, that earned a 3-1 aggregate success and sent them to next month’s final in Prague, prompted a gang of black-shirted, hooded AZ ultras to attempt to storm into the area reserved for friends and family behind the dugout.

Players including Michail Antonio, Said Benrahma, Aaron Cresswell and Flynn Downes climbed over the advertising hoardings in a bid to stop the trouble.

The governing body’s disciplinary panel will wait for the relevant reports before deciding on any action, but the PA news agency understands that given the severity of the disorder, it could follow previous cases and an inspector may be appointed to investigate more thoroughly.

Given the extensive video footage of the ugly scenes the Dutch club could face heavy sanctions.

The local police are investigating the incidents in a bid to identify the supporters but they are yet to apprehend any of the hooligans.

In a statement they said: “So far, no arrests have been made. Our aim was to disperse the crowd and restore order as quickly as possible, in which we succeeded. The police will investigate footage of the incidents and try to identify supporters. Arrests may follow from this.

“Together with AZ, the municipality of Alkmaar and the public prosecution service we will evaluate last night’s incidents, which we regret having happened. This kind of behaviour has no place in football.”

Hammers boss David Moyes, whose 87-year-old father David Snr was at the match, said: “I can’t explain what happened and why it happened.

“I can only say the players were involved because it was the family section and most of their family and friends were in there. That was probably the reason for the reaction.

“Was I worried? Yeah, my family were there and I had friends in that section. You’re hoping they would try and get themselves away from it.

“I didn’t recognise it because I’d gone onto the pitch. Security wanted to take me inside, but I had to make sure my players weren’t involved.”