British regulators have fined Royal Bank of Scotland PLC 56 million pounds ($87 million) for computer problems that made it impossible for customers to get access to their accounts.

The Financial Conduct Authority fined the state-owned bank for failing to put in place systems that could "withstand or minimize the risk of IT failures." The Bank of England's Prudential Regulatory Authority, also leveled a fine — its first since coming into existence in 2013.

The PRA says the breakdown had the "potential to have an adverse effect on the safety and soundness of RBS, Natwest and Ulster Bank."

The incident began on June 18, 2012, with some systems disrupted into July. Some 6.5 million customers were affected.

The bank was rescued by the taxpayer during the 2008 financial crisis.