Terrifying ISIS Champions League threat prompts Spanish police to activate ‘all alert systems’ in massive security operation ahead of Real Madrid's quarter-final fixture against Man City

The Premier League title holders are due at Santiago Bernabeu on Tuesday. Arsenal will be in action at the same time, as they prepare to welcome Harry Kane and Bayern Munich to Emirates Stadium. Every effort is being made to ensure that those matches pass without incident.

In Spain, La Vanguardia reports that more than 1,270 security personnel have been deployed to the nation’s capital. Those measures are being taken amid heightened threat from ISIS and potential attacks on prominent fixtures in elite European competition.

Head of The Ministry of the Interior, Fernando Grand-Marlaska, has said: “In terms of preventing the terrorist threat, the State Security Forces and Bodies have activated all their early warning and protection systems, as well as all their response mechanisms ready and willing.” More than 2,000 agents from the National Police and Civil Guard will be joined by members of the Municipal Police in helping to keep players, coaches and spectators safe.

ISIS have allegedly threatened to attack at all four Champions League quarter-final ties, including Emirates Stadium ahead of Arsenal's meeting with Bayern Munich - as The Telegraph reports. European football's main governing body UEFA have reacted in an official statement, which reads: "UEFA is aware of alleged terrorist threats made towards this week’s UEFA Champions League matches & is closely liaising with the authorities at the respective venues. All matches are planned to go ahead as scheduled with appropriate security arrangements in place."

The massive security operation in Spain will extend to Atletico Madrid’s meeting with Borussia Dortmund on Wednesday, which takes place at the 70,460-capacity Metropolitano Stadium, while Paris Saint-German will be playing host to La Liga giants Barcelona in the other quarter-final encounter.