The CEO of challenger bank Monzo has issued a frank apology to users after a run of card outages left some unable to make payments at times this week.

Tom Blomfield admitted in a customer-wide email sent out on Friday that people “lose trust in [Monzo]” if they can’t use their cards.

“These outages are unacceptable,” he said. “I want to personally recognise that and apologise on behalf of the whole company.”

The co-founder explained that the incidents, which have been caused by Monzo’s card processor, could continue for the next few days.

“We don’t know how long it will take our card processor to fix the issues, but we will always keep our status page up to date,” he said.

The incidents have lasted from a couple of minutes to over an hour, according to the email.

But Blomfield said that those trialling Monzo’s new current accounts, which are set to be rolled out to all users by the end of the year, have not been affected by the incidents.

“We believe it will be a more stable base on which to run the bank,” he added.

Last week the CEO told an audience of customers at the startup’s HQ that it had turned down two acquisition offers in the last month, adding that “selling out to a big bank is not why we’re here”.

“We’re here because we believe we can build something that genuinely improves the lives of millions of people around the world, and ultimately a billion,” he said.

“If we sell out to a big bank we will not achieve that goal.”