MILLWALL were placed on the highest terror alert last month over fears of a plot to attack The Den.

Club bosses were tipped off after discovering a member of staff, who converted to Islam, had been sending mobile phone footage of the Lions’ stadium to a pal in Pakistan.

5 Millwall was placed on the highest terror alert last month over fears of a plot to attack The Den Credit: Rex Features

5 Counter-terror cops placed The Den on highest level of alert of any stadium Credit: PA:Press Association

The employee’s Facebook page contained screen grabs of the FaceTime conversation as well as links to the controversial Finsbury Park Mosque.

Millwall suspended the worker and called in counter-terror cops, who swiftly raised the threat level to the highest level for any club.

The member of staff, a middle-aged man who has worked at the club for over a decade, was admitted to hospital with concerns about his mental health.

He was spoken to by cops but not arrested. He has been discharged from hospital but remains on sick leave.

5 Millwall had increased security for their Championship clash with Reading last month Credit: PA:Press Association

5 Millwall fans were believed to have been at risk of a terrorist attack in September Credit: Rex Features

The club increased security for their subsequent home games against Reading on September 26 and Barnsley last Saturday.

A source said: “The alert was raised by a member of staff and the club was quick to head off any possible threat.

“The police took it really seriously and plain-clothes officers have been trawling the stadium speaking to staff.

“Security was stepped up across the club but police have said there’s no direct threat.”

5 Millwall are feared to have become a target for terrorists after lifelong fan Roy Larner was lauded as a hero following London Bridge attacks Credit: Darren Fletcher - The Sun

Millwall are feared to have become a target for terrorists after lifelong fan Roy Larner, 47, was lauded as a hero for taking on the London Bridge attackers in June.

In a statement, Millwall said: “Millwall FC wishes to stress to its supporters and staff that anti-terror police units, after a thorough and exhaustive investigation, have found no evidence of a direct or indirect threat to the football club, its stadium, employees or fan base.

“The club wishes to praise the individual who brought information to its attention which led to the immediate suspension, pending further investigation, of a member of staff.

“That employee is now on sick leave and it would be inappropriate to provide any details of their condition. No arrests have been made.

“The club has reviewed and furthered already rigorous existing security measures and will continue to work closely with the police and its security team to ensure the safety of all those associated with Millwall.”

A Met Police spokesman said: “We would like to reassure the public that we constantly review security plans for public events, taking into account specific intelligence and the wider threat.

“Our priority is the safety and security for all those attending or involved, the public are encouraged to continue with their plans to attend or take part in events as normal.

“We do not discuss specific security arrangements as this would be extremely unhelpful in our ongoing efforts to counter terrorism.”