An Islamic State sleeper cell has plans to carry out attacks targeting English and Russian football fans at Euro 2016 during a match in Marseilles, data retrieved from the main Paris attacks suspect's laptop reveal, according to the Sun.

Photos retrieved from the computer found during a raid in Brussels and belonging to Salah Abdeslam, reportedly point to the French city of Marseilles, where England is scheduled to play Russia on June 11.

The information also allegedly disclosed that Islamic State (IS, formerly ISIS) was considering using drones “possibly” armed with chemical weapons, as well as suicide bombs and AK47s to carry out mass attacks, the Sun reports citing its sources.

Despite Abdeslam’s capture, authorities fear other ISIS-linked cell members could still proceed with the plan.

“Most of the information was contained in Abdeslam’s personal testament setting out his wishes in the event of death,” a Belgian security source told the Sun.

The gathered information is making authorities believe that the primary target of terrorists will be the English team’s fan zone in the Old Port quarter of the city.

“This can only mean plans were being drawn up to attack England and Russia fans before the game. England and Russia fans are obvious targets, because both countries are bombing IS in Syria and Iraq,” the source added.

“Drones are mentioned on the computer, but it’s not clear how they might have been used in an attack — possibly armed with chemical weapons.”

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Football fans may also potentially be targeted in indiscriminate shooting at bars and other entertainment venues in the city. UK security chiefs fear IS may try to gun down England supporters as they enjoy a drink in bars outside the official fan zone.

“What they might attempt outside of the secure zones is what worries us most. Bars full of happy, drunk blokes are a very soft target. We are working extremely closely with the French,” a senior Whitehall source told the Sun.

“A more conventional Paris-style assault on thousands of fans in bars before the game is seen as much more likely,” the Belgian source concurred.

The terror attacks rocked the French capital on November 13, 2015, killing over 130 people and injuring hundreds of others. Three suicide bombers carried out an assault near the Stade de France in Saint-Denis, which was followed by suicide bombings and mass shootings at cafés and restaurants. Of the 130 victims, at least 89 were killed in the Bataclan Theater, where the jihadists took hostages before engaging in a stand-off with police officers.

Fears of a Paris-style assault have also been confirmed to the publication by a police source, who said that “Marseille is the Kalashnikov capital of France, and there are plenty of potential IS recruits here.”

More than 1,000 police officers will be deployed to offer security for the duration of the competition in Marseilles, with snipers deployed throughout the city. Shoulder-mounted Mistral surface-to-air missile launchers will also be used for security, positioned at the city’s strategic points, the publication reports.

“Officers will be authorized to intervene the moment a terrorist is identified,” another senior security force officer told the Sun. “Terrorism is our main security priority.”