An investigation has been launched by Reform UK into the social media activity of Staffordshire County Council’s leader after it was alleged he made racist comments online.

Activist group Hope Not Hate claimed to have found racist posts on an account on X allegedly linked to Ian Cooper, including one about former foreign secretary David Lammy which read: “No foreign national or first generation migrant should be allowed to sit in Parliament.”

Reform said it was undertaking an “urgent internal investigation over Cooper’s non-disclosure of social media accounts”.

The BBC has made two approaches to Cooper for comment, but he has not responded.

BBC Verify analysed the X account, which is under the name Ian Cooper. It is not possible to definitively confirm it is the council leader as it does not feature a picture or reference to his position, though it is likely due to the followers linked to the account.

Cooper is not the first of Staffordshire’s Reform councillors to face scrutiny over their social media activity.

Cabinet member for highways Peter Mason apologised last month for his choice of words over posts he wrote about black women and the police.

Nine of Labour’s Staffordshire MPs have called for Cooper’s resignation.

They said in a statement: “Ian Cooper has, by sharing this kind of material, exposed his far-right and racist opinions. He should now resign the leadership and his seat.

“No wonder he was reluctant to take action against councillor Peter Mason given his own racist and repugnant views. Staffordshire deserves better than this outright bigotry. “

Cooper’s alleged activity on Facebook has also come under scrutiny after a group called Reform UK Exposed claimed he was a top fan of a page called The European Race, which promotes white supremacy.

A top fan is someone who has high engagement with a Facebook page.

The BBC understands complaints have been submitted to Staffordshire County Council from various political groups on the authority about Cooper’s alleged social media activity.

The council said it would not comment on individual complaints.

The leader of the council’s Conservative group, Philip White, said: “A man who is a ‘top fan’ of a white supremacist Facebook group is completely unfit for public office and he should resign immediately.”