Former county council leader David Parsons is contesting claims he owes more than £4,000 for unpaid travel expenses.
Leicestershire County Council gave the former Tory councillor until Wednesday to pay back the outstanding amount.
However, County Hall officials were instead served with a legal letter from Coun Parsons' solicitors challenging their £4,089.84 invoice.
County Hall claims Coun Parsons was collecting travel expenses from the council for trips to Europe while also receiving allowances from the European Union.
A council spokeswoman said: "Mr Parsons had received a flat-rate travel allowance from the (European Union) Committee of the Regions.
"This had been to cover those costs he incurred in travelling to and from the point of departure in the UK.
"In most cases, such travel had been provided at the county council's expense and at no cost to Mr Parsons.
"Mr Parsons had, however, continued to receive the allowance and had therefore received a double benefit for such journeys."
Coun Parsons, who resigned from his post and was expelled from the Conservative Party following an investigation into his expenses, said he would fight efforts to reclaim the cash.
He has been invoiced for six outstanding payments.
Since January, he has paid back five – totalling £6,595 – which includes money for using the civic car to take him to and from two family weddings.
However, he disputes the sixth debt which relates to the transfers while travelling abroad.
He said: "I completely refute the invoice and my solicitors have served a letter to the county council to that effect.
"The county council has acknowledged receipt of the letter and said it would respond accordingly."
The council spokeswoman said: "A letter from solicitors acting for Mr Parsons has been received and we will be responding in due course."
In June, Coun Parsons appeared before County Hall's standards committee facing allegations he kept hold of money paid to him for trips to Europe which he should have reimbursed to the authority.
The council said that at one point he had more than £5,400 sitting in his bank account which should have been paid to the council.
The committee found he had breached five conditions of the code of conduct and strongly censured him.
