A watchdog group has asked Congress to investigate Betsy DeVos as to whether she knew about her brother’s plans after it was claimed he hired spies to infiltrate a teachers’ union.

The New York Times reported on Saturday that Ms DeVos’ brother Erik Prince, hired an ex-spy to help him infiltrate a Michigan-based office of the union, the American Federation of Teachers.

Accountable.US wrote to the US House committee on oversight and reform on Tuesday and asked them to investigate the claims.

In regards to what Mr Prince has ben accused of, a spokesperson for Ms DeVos told Politico: “Secretary DeVos has absolutely nothing to do with this.”

In their letter, Accountable.US requested that the committee investigate whether Ms DeVos was involved “in efforts to recruit former intelligence officers to spy on the activities of the American Federation of Teachers”.

The watchdog group went on to accuse Ms DeVos and her husband of having previously funded an organisation attempting to discredit teachers’ unions.

“DeVos and her husband have previously funded at least one organisation in Michigan which targeted unionised teachers with advertising campaigns and encouraged them to drop out of their unions.” said the letter.

The group, who describe themselves as “a nonpartisan watchdog group that is uncompromising in our search for the truth”, go on to say in the letter that it is in the public’s best interest that Ms DeVos is investigated.

“We believe it is in the best interest of America’s children, parents, and teachers for them to understand exactly what steps Betsy DeVos has taken behind the scenes to try to discredit teachers’ unions who advocate for strong public schools,” wrote the group.