The increasingly fractious dispute between Charlton fans and the owners of the club has taken a sinister turn.

The resignation of their chief executive Katrien Meire, 31, has been posted on Companies House – a bogus document says the club which will be investigating “as it is something we take seriously”.

Companies House, the formal register for developments within limited companies, says the documents “satisfied the required checks” and were received in good faith. But the signature on the document – which purports to terminate her position in December – appears to be a fake.

Belgian Meire joined Charlton’s board of directors in January 2014 when Roland Duchatelet, 69, took over the club, now at the bottom of the Championship.

She has been the target of ire from the protest group Card (Campaign Against Roland Duchatelet) which has stepped up its actions in recent weeks and plans more protests after the Charlton match against Cardiff on Saturday (February 13).

In a statement on February 8, Card said: “Off the pitch, the club is in an even worse state, with chief executive Katrien Meire responsible for a series of PR gaffes, including the labelling of fans’ affinity for the club as ‘weird’ at a Dublin web conference in November.”

However, Card denies any involvement in any forgery and has repeatedly stated its aim was legitimate protest, saying that illegal or anti-social protests were self-defeating.

A message on Twitter said: “This one wasn’t down to Card, but Meire’s decision to comment was jaw-droppingly daft.”

Under the Companies Act 2006, an individual found guilty of filing false documents to Companies House could receive a prison term of up to two years, a fine, or both.