The concerns raised by the Insights Association, and included in a letter to congress leaders, comes as various federal websites and data have been unavailable or unreachable over recent weeks, sometimes temporarily, including at the US Census Bureau.

The issues with access to public data and websites have followed the creation of a Department of Government Efficiency, headed by X owner Elon Musk, which has been introduced by US president Donald Trump to cut government spending.

However, the department has been heavily criticised in some quarters for its access to public data and its alleged deletion of information from federal websites, especially related to climate change and diversity, equality and inclusion.

The letter to congress said that the more than 230 signatories had “concern and strong opposition to the recent incidents in which public data have been selectively removed from federal websites”.

Websites involved include those for the US Census Bureau, Centers for Disease Control and Prevention, Department of Health and Human Services, Office of Justice Programs, and the Office of Scientific and Technical Information.

The letter added that researchers have been attempting to reconcile previously archived versions of the websites to discern fluctuations and what may have been lost or removed.

The disappearing data sets constitute, according to the letter, a “violation of trust… done without regard for legal and administrative precedent”. 

The letter continued by pointing out that “removing or curtailing access to these data, even temporarily, erodes the public trust that federal statistical and scientific agencies have earned” and “deny the public of scientists and other independent analysts use of federal data so important to public and private sector leaders in their work”.

Finally, the letter called upon congress “to demand the complete restoration of any federal data that have been removed and to work with the administration to prevent any future purge or removal of data from federal agency websites and portals”.

The letter was led by the Population Association of America, the American Statistical Association, and the Council of Professional Associations on Federal Statistics.

Howard Fienberg, senior vice-president advocacy for the Insights Association, said: “There should be no conflict between the policies of the Trump Administration and the unrestricted public access to crucial American Community Survey and census data, especially data related to race, ethnicity and other key demographic factors.

“This information is vital for creating representative statistical samples for research studies across the US. The diverse applications of census data in both the public and private sectors should not be subjected to unrelated policy agendas.”