Chelsea have called on West Ham United "to deliver a safe event" ahead of Wednesday's League Cup clash at London Stadium, a fixture with a history of crowd trouble that is viewed as a major test of security at the Hammers' new ground.

Security has been tightened for the fourth round game between the teams from east and west London, with a new police radio communications system installed, restrictions on alcohol sales and the deployment of more than 1,000 stewards at the 60,000-seat stadium.

Outbreaks of trouble have already been recorded at West Ham's Premier League games against Watford, Sunderland and Middlesbrough this season, and fears have been raised of a repeat with 5,000 Chelsea supporters expected to travel.

"In light of recent incidents at the stadium there will be much attention on the fixture and especially on the conduct of supporters from both clubs." read a statement on Chelsea's website (www.chelseafc.com).

"We understand this is the first time a game of this magnitude has taken place there and we are looking at West Ham United and the local authorities to deliver a safe event.

"We appreciate there is a long-established rivalry between these two London clubs but we ask all supporters to remain respectful and refrain from any form of offensive or discriminatory behaviour."

The police said there will be "a robust" presence of officers if required inside the former Olympic Stadium. 

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