The investigation focuses on collapsed business Signature Group in relation to a suspected £140m fraud, involving 1,000 investors who made investments in hotel developments.

Signature Group collapsed in April 2020, with losses of £140m, including debts of more than £40m owed to unsecured creditors and £90m in outstanding intercompany loans.

The SFO investigation centres around Signature Group’s investment schemes which targeted UK and international investors to raise funds to redevelop iconic landmarks including Millennium House in Liverpool with its centrepiece Shankly Hotel development, Belfast’s Scottish Mutual Building and the Coal Exchange in Cardiff. It even had plans for a cruise liner that was marketed as a ‘flotel’ to be moored off Canary Wharf in London and travel to Ibiza.

The Signature Group operated for over seven years, buying up predominantly historic buildings across the UK for redevelopment into luxury hotels, residential apartments and office spaces.

Investors loaned money to Signature or purchased a hotel room, apartment or office space in one of the group’s properties, with promised returns on their investment of between 8% and 15%.

The four people arrested have not been named and will be questioned at police stations across the northwest.

Nick Ephgrave QPM, director of the Serious Fraud Office, said: ‘The scheme offered attractive returns and used much-loved local landmarks to lure investors.

‘We have people up and down the country left out of pocket, and buildings left derelict at the centre of our cities.

‘Today’s arrests and searches will help us reconstruct exactly what happened. This is now an active criminal investigation.’

The SFO operation was supported by the National Crime Agency (NCA).