The City watchdog has confirmed it does not yet know whether thousands of UK customers' money is safe after the spectacular collapse of German payments company Wirecard.
Customers of a host of UK fintech firms, including card providers Curve and Pockit, use Wirecard's technology to process payments.
The Financial Conduct Authority (FCA), ordered Wirecard's UK arm to stop making payments on Friday to prevent it potentially disposing of any funds after it emerged that €1.9bn was missing from the company's accounts.
The move effectively froze the accounts of hundreds of thousands of UK consumers leaving them unable to access their cash.
On Monday, the regulator issued an update saying: “We are maintaining pressure on the firm to resolve these issues which would allow it to operate under certain conditions.
“However, we cannot lift the restrictions without reassuring ourselves that the firm has been able to satisfy all our concerns for example that all clients' money is safe. We hope to be able to issue an update soon.”
The FCA said it had been working with Wirecard, and other international and UK authorities.
“We have seen good progress by the firm in meeting the conditions we set,” the watchdog said.
Martin Lewis, founder of consumer website moneysavingexpert.com, said there is a reasonable expectation that the hundreds of thousands of consumers affected will get access to their money again by Wednesday or Thursday.
Curve issued a statement on Sunday night saying its customers would be able to make payments again from Monday.
Wirecard's rapid collapse into administration amid allegations of fraud has shocked markets and put the spotlight on auditor EY.
The Financial Times revealed on Friday that EY had failed to verify Wirecard's bank statements for three years, a task considered to be a basic requirement for any audit.
Wirecard's former chief executive Markus Braun was arrested on suspicion of falsifying company revenue to make the company appear healthier than it was.
It came after the company said that €1.9bn (£1.7bn) stated in its accounts likely never existed.