Ajax have apologised for the incident which saw AZ Alkmaar goalkeeper Esteban attacked by a pitch invader.

The fan targeted the Costa Rican after running on to the playing area 37 minutes into the KNVB Beker clash at the Amsterdam ArenA.

Esteban, 22, responded by kicking the fan to the ground, leading him to be shown a red card by referee Bas Nijhuis.

Livid AZ coach Gertjan Verbeek called his players from the field, with them subsequently leaving the ground and forcing Nijhuis to abandon the game.

Ajax director Jeroen Slop told the club's official website: "This was a terrible incident and we deeply regret it and offer our sincere apologies.

"The supporter has been handed over to the police. It was a 19-year-old man who was probably under the influence of alcohol. He said he hated the AZ goalkeeper and had therefore attacked him."

According to Slop, Ajax gave AZ assurances about their safety after the incident but the visitors opted not to resume the match.

He said: "Ajax offered to put additional stewards around the pitch to ensure their safety and play the game but AZ stuck to their decision."

The Dutch FA (KNVB) must now decide what action, if any, to take.

A statement read: "The case has been submitted to the prosecutor of football. He will see if there is guilt and report his findings.

"There are three options: the game is played [completed], the game is replayed, or the respective position is regarded as the final score."

Ajax were leading 1-0 at the time of the abandonment.