Former directors of the Co-operative Bank face fines and bans from the financial services industry after two more investigations into the events leading up to its £1.5bn bailout were announced .

The Bank of England's regulation arm, the Prudential Regulation Authority, and the City regulator, the Financial Conduct Authority, made formal announcements of enforcement investigations into the events that led to a £1.5bn capital shortfall being revealed last June. The investigations could take months to complete and mean that an independent review commissioned by George Osborne in November will be delayed until decisions are made about whether to take any action against the bank and its former management.

Investigations into other bank problems have taken years. The outcome of an investigation into the rescue of HBOS by Lloyds TSB in September 2008 is not expected to be published until this summer while the report into Royal Bank of Scotland was published three years after its taxpayer bailout. The investigations may find no personal wrongdoing. For instance, no individual at RBS was found to be legally responsible for its near collapse while at HBOS only former banker Peter Cummings has been fined £500,000 and banned from working in the City.

After a £1.5bn capital shortfall was identified by the PRA, the Co-op bank had to be rescued by bondholders – including US hedge funds and as a result the Co-operative Group of supermarkets, pharmacies and funeral homes has been left owning just 30% of the bank. A stockmarket flotation of the bank is possible this year and the new management said they were working with the regulators. "The new management team had to rectify the difficult and complex issues that they have inherited," the bank said.

The PRA said it was "undertaking an enforcement investigation in relation to the Co-operative Bank and as part of that investigation will consider the role of former senior managers.… The Treasury has previously indicated that the independent review announced by the chancellor will not start until it is clear that it will not prejudice any actions that the regulators may take."

The FCA said its investigation would look at decisions and events up to June 2013. "The independent review announced by the chancellor will commence once it is clear that it will not prejudice any actions that the regulators may take. This sequencing is necessary to ensure that the outcomes of the enforcement work are not prejudiced and follows the approach taken for both the RBS and HBOS reports," the FCA said.

The investigation by the FCA – which could go back as far as 2006 – is expected to include further analysis of information provided by the Co-op bank to its shareholders about its capital position in its financial statements. The accountancy regulator, the Financial Reporting Council, is yet to decide whether to launch a formal investigation.

The crisis at the bank – which had prided itself on its ethical approach to business – deepened at the end of last year when its former chairman Paul Flowers was arrested following a Mail on Sunday report that showed a video of the 63-year-old Methodist minister handing over cash to apparently buy drugs. The report appeared just days after he had appeared by the Treasury select committee of MPs, which will continue its investigation into the Co-op's aborted attempt to buy 631 branches from Lloyds Banking Group. Clive Adamson, director of supervision at the FCA, is scheduled to appear before MPs to discuss the role of regulators in the ill-fated attempt by Co-op to take control of branches, codename Verde.

The situation sparked a political row about whether the coalition encouraged the aborted attempt to buy 631 branches from Lloyds Banking Group and whether the previous Labour government had championed Co-op's ill-fated merger with Britannia Building Society in 2009. It also generated concerns about the way the mutual Co-op Group is governed.

Last month Lord Myners, the former City minister and one-time chairman of Guardian Media Group, was appointed to overhaul the structure of the Co-op, the country's biggest mutual.

Co-op inquiries

• Internal review (commissioned by the Co-op) by Sir Christopher Kelly

• Review (commissioned by the Co-op) into corporate governance by new non-executive director Lord Myners

• Independent investigation ordered by George Osborne, which will not start until Prudential Regulation Authority (PRA) and Financial Conduct Authority (FCA) complete their work

• Financial Reporting Council, the accountancy regulator, is looking at financial statements but has not launched a formal investigation

• Treasury select committee investigation into the Co-op's attempt to buy 631 branches from Lloyds Banking Group

• Enforcement investigation by PRA

• Enforcement investigation by FCA