The statistics watchdog is investigating allegations the Prime Minister and Home Secretary falsely claimed crime had fallen under their leadership.

The UK Statistics Authority confirmed it has opened a case into comments made by Boris Johnson when he said in the House of Commons “we have been cutting crime by 14%” as well as a Home Office press release which said the latest data showed “crime continues to fall under this government”, quoting Priti Patel as saying it demonstrated the Government’s approach “is working”.

An authority spokesman said it was looking into a complaint made by Alistair Carmichael, the Liberal Democrat home affairs spokesman and former cabinet minister, and will provide an update in due course on its findings.

Despite a fall in most crimes during coronavirus lockdowns, some are now reaching or exceeding pre-pandemic levels – with rises in some offences like fraud offsetting reductions seen elsewhere, the Office for National Statistics (ONS) said last week.

Police recorded 5.8 million crimes in England and Wales in the 12 months to September, a 2% increase compared with the previous year (5.7 million). Excluding fraud and computer misuse, the figure falls 1% (from 4.95 million to 4.92 million) in the same period.

The figures show police recorded the highest number of rapes and sexual offences in a 12-month period while separate Home Office data detailed how the proportion of suspects being taken to court has fallen to a new record low and remains the lowest for rape cases.

Meanwhile the results of the latest crime survey for England and Wales – research carried out by the ONS – estimates a 14% increase in total crime, “driven by a 47% increase in fraud and computer misuse”, for the year ending September 2021 compared with the 12 months to September 2019. Excluding fraud and computer misuse, crime decreased by 14%, “largely driven by an 18% decrease in theft”.

Mr Carmichael reported Mr Johnson and Ms Patel to the authority for “falsely claiming” a reduction in crime, The Times newspaper said.

He reportedly wrote to UK Statistics Authority chairman Sir David Norgrove asking him to investigate the “gross misrepresentation”, adding: “Victims of fraud have been let down and ignored for too long, and writing them out of the story only makes that worse.”

The watchdog works to “promote and safeguard official statistics to serve the public good”, including “regulating the quality and publicly challenging the misuse of statistics”.

It can intervene if it considers a politician or government department has misused or misrepresented figures and has not adhered to a code of practice.

The Cabinet Office’s Ministerial Code of Conduct says: “It is of paramount importance that ministers give accurate and truthful information to Parliament, correcting any inadvertent error at the earliest opportunity. Ministers who knowingly mislead Parliament will be expected to offer their resignation to the Prime Minister.”

It adds: “Ministers need to be mindful of the UK Statistics Authority’s Code of Practice which defines good practice in relation to official statistics, observance of which is a statutory requirement on all organisations that produce National Statistics in accordance with the provisions of the Statistics and Registration Service Act 2007.”

According to The Times, the Home Office said its press release made clear that the figures excluded fraud. The release said between June 2019 and September 2021, crime fell by 17%, excluding fraud and computer misuse.