The head of the Passport Office, Paul Pugh, has strongly denied that his organisation is in chaos despite the backlog of applications standing at 508,000.
Pugh told the Commons home affairs select committee that the "vast majority" of applicants were being issued with passports within three to four weeks.
He told MPs that the number of "work in progress" passport applications had fallen from 537,000 in the week ending 22 June to 508,000 at the end of last week as the Passport Office expanded its capacity.
"The organisation is not in chaos, we are continuing to issue to our customers over 170,000 cases per week," said Pugh. "To the end of June, for straightforward renewals, 94% were within three weeks and 98% within four weeks."
But the committee's chairman, Keith Vaz, pointed out that the current backlog of 508,000 was still 20,000 higher than the 483,000 figure for "work in progress" for 1 June, when the home secretary had to announce a package of emergency measures to deal with the passport crisis.
Pugh, the Passport Office chief executive, also confirmed that an unforecast surge in applications so far this year was likely to lead to the operation making a £50m surplus for the second year running. Pugh hinted that this might lead to a reduction in the current £72.50 adult renewal fee.
He told the MPs that 4.2m applications for new passports and renewals had been received so far this year compared with the 5.6m usually seen in an entire year. He said they had received 775,000 applications in June alone – the highest ever total in a single month – and more than 100,000 higher than the figure for June 2013.
"We have seen in the last four months, every single one of those months, the intake has been higher than the highest month of the year in preceding years," he said.
But the chief executive admitted the Passport Office did not know what had caused the surge: "Clearly our forecast intake for the year has been substantially exceeded during this period.
"We don't fully understand why that is. We believe it to be more to do with the seasonality of demand rather than the total of demand."
He confirmed however that "freakish levels of overtime" costing up to £5m were now being paid out as passport offices around the country worked up until midnight and over weekends to try to meet the backlog.
