The boss of British Gas's owner, Centrica, said "there is no excuse" after an investigation found the company sent debt collectors who broke into vulnerable customers' homes to install prepayment meters.
A Times investigation showed a company used by British Gas to pursue debts, Arvato Financial Solutions, forcing their way into homes to fit the devices, despite signs children and disabled people were living there.
Chris O'Shea also said that customers do not deserve to be treated in such a way, and that he would not "justify it" - adding that he is launching an independent investigation.
"I am really, really sorry," he added, talking to Sky News' business presenter, Ian King.
"We've clearly got it wrong here and we are going to fix that."
He said he felt "disappointed, livid and gutted" at undercover footage from the investigation, by The Times newspaper, which includes one debt collector saying "this is the exciting bit... I love this bit", as a locksmith prepares to force a door.
"This is not who I am, this is not the standard I set myself, it's not the standards I set the company, it's not who we are, it's not how we do business, there's no excuse," Mr O'Shea added.
Meanwhile, the prime minister's official spokesman called the reports "deeply shocking and concerning" and confirmed the energy minister was meeting British Gas on Thursday afternoon.
"Vulnerable families should not be treated so poorly, British Gas has rightly now suspended this practice," he said, before adding: "There are circumstances in which prepayment meters are allowed but it does not appear, from reports, that this is happening in this case."
Ofgem, the energy regulator, is launching an urgent investigation into British Gas following the allegations.
"These are extremely serious allegations from The Times. We are launching an urgent investigation into British Gas and we won't hesitate to take firm enforcement action," an Ofgem spokesperson said.
The Times reported that British Gas customers who had prepayment meters fitted by force included a woman in her 50s described in job notes as "severe mental health bipolar" and a mother whose "daughter is disabled and has a hoist and electric wheelchair".
In its undercover investigation, the paper also alleged that Arvato Financial Solutions employees were incentivised with bonuses to fit prepayment meters.
Business Secretary Grant Shapps said he was "horrified" by the report and asked Graham Stuart, the energy minister, to hold a meeting with the company.
Shadow climate and net zero secretary Ed Miliband said: "It's right that you are horrified. Now do something about it and BAN the forced installation of prepayment meters this winter. What are you waiting for?"
In its statement, Centrica said it would complete a "thorough investigation" and the warranty suspension would last "until at least after winter".
Meanwhile, Arvato Financial Solutions told the Times it "acts compliantly at all times in accordance with the regulatory requirements" and the findings did not represent the company's views or its official guidance on how to interact with customers.
A spokesman told the paper: "If there has been any verbal or any other type of misconduct by individual employees, we deeply regret it."
According Ofgem, getting a court warrant to force-fit a prepayment meter should be a "last resort" after "all reasonable steps have been taken to agree payment".
It said suppliers cannot force-fit a prepayment meter under warrant for people in "very vulnerable situations" if they do not want one and they cannot use warrants "on people who would find the experience very traumatic".
Last week, Ofgem announced it is to review the checks and balances that energy firms have around placing customers on prepayment meters, warning it will take further legal action if it finds they are not taking due care.
According to Citizens Advice, an estimated 3.2 million people across Britain ran out of credit on their prepayment meter last year because they could not afford to top it up.