Tesco chief executive Dave Lewis has said he will investigate the profit overstatement of his company "right to the end" until he gets to the bottom of it.
Mr Lewis said it was "one event" which occurred in the first half of 2014 totalling around the £250 million mark and he would update the market when he knew more.
Tesco boss Dave Lewis has said he will not know exactly what went wrong with their profit misstatement until he gets the results of an independent investigation into the matter.
The chief executive, who was only appointed three weeks ago, was made aware of the issue on Friday and four employees have since been "asked to step aside".
But he would not reveal who the staff members were and said disciplinary action had not been taken against them.
Asked if the deficit could be more than the £250 million the firm reported in their figures, he said: "Early indications suggest it is £250 million.
"But I must stress at this point in time I won't know until we've done the full investigation.
"It's a obviously a very serious issue which is very important for us but until I've finished the investigation I can't speculate exactly what happened."
Tesco chairman Sir Richard Broadbent has said he has no intention of stepping down despite the slump in Tesco's performance and revelations over misstated profits.
He said: "I do not think we are ducking the issues. My intention is to continue to be part of the solution."
The company is currently without a finance director as Alan Stewart is not due to join from Marks & Spencer until December 1 and Laurie McIlwee left the business this month.
It said it had alerted City regulator the Financial Conduct Authority to the developments.
Tesco chief executive Dave Lewis today declined to confirm reports that UK managing director Chris Bush was among the four members of staff suspended over the profits scandal.
However, he confirmed that Tesco's multichannel director Robin Terrell will lead the UK team.
He added: "We have asked four people to step aside so we can be sure we do the fullest and frankest investigation."
The investigation, which centres on timing issues relating to income received from suppliers, was brought to the attention of Tesco's general counsel by a whistleblower on Friday.
The company carried out a preliminary investigation over the weekend before issuing its profits warning earlier today.
Tesco has suspended four employees while the company investigates how their profits came to be overstated by £250 million.
The supermarket made the shock admission today after "finding a problem with its accounts".
The four people, who worked across commercial and operations will step down from their roles while a review is carried out.
Tesco declined to comment.
Tesco have said "a number of staff" have been asked to step down while an investigation is carried out after the shock admission today that they overstated their half-year profits by £250 million profit.
A City analyst has said he is "flabbergasted" by the Tesco profit overstatement of £250 million.
Shore Capital retail analyst Clive Black said: "These are serious times for Tesco and its shareholders."
Tesco shares, which have already fallen by 39% over the last year, slumped by another 11% today.
Tesco has ordered auditor firm Deloitte to undertake an "independent and comprehensive" review of their half-year profits after revealing they overstated them by £250 million.
The "error"' involved the accelerated recognition of commercial income and delayed accrual of costs.
New chief executive Dave Lewis, who started in the role on September 1, said: "We have uncovered a serious issue and have responded accordingly.
"The board, my colleagues, our customers and I expect Tesco to operate with integrity and transparency and we will take decisive action as the results of the investigation become clear."
Tesco has launched an investigation after revealing it overstated its profits for the last six months by around £250 million.