One of the giants of Scottish Labour has warned claims of "electoral irregularities" in last year's general election could bring his party in to disrepute.

Lanarkshire kingpin Jim McCabe is one of more than a dozen party stalwarts to warn the Labour leadership of the finances of a local constituency group in what some insiders describe as a "smear".

The former North Lanarkshire Council leader - who stood down in February after 18 years in post - is one of several councillors to sign a letter to his party's Scottish HQ flagging up worries over discrepancies in the accounts of the Motherwell and Wishaw Constituency Labour Party (CLP).

The letter, written by Councillor Frank McKay last month and seen by The Herald, refers to reports that there were nearly £4500 of donations to the CLP that it could not account for during the general election year.

That has sparked fears in the party that Labour could have breached legally binding spending limits as it fought, unsuccessfully, to save the seat of its sitting MP, Frank Roy. However, an investigation ordered by the party's Scottish general secretary, who happens to be Mr Roy's son Brian, found no problem with election expenses.

Party insiders, nevertheless, stress the the very fact a figure as big as Mr McCabe signed the letter reveals the "sheer depth of animosity" inside North Lanarkshire Labour.

The main target of the letter are Mr McCabe's successor, Jim Logue, and his deputy leader, Paul Kelly, a previous chairman of the Motherwell and Wishaw CLP. It accuses the new administration of "hypocrisy, aggression and cynical self-interest".

The letter, dated March 15, adds: "We are of the opinion that there are very serious questions marks around the depute leader. We believe that the severity of these threatens to bring the party in Scotland in to disrepute.

"As you are aware the Motherwell and Wishaw CLP has raised questions...about the conduct of the accounts while he was election agent

"Whilst we do not allege misappropriation, we do allege severe incompetence.

"We are concerned that the deputy leader was allowed to stand....at a time when opposition colleagues are speculating on the possibility of electoral irregularities."

This letter came after Mr Logue carried out a radical reshuffle of the council's leadership, prompting four councillors to quit the party.

Sources close to the administration described the allegations about the CLP finances as a "smear" by some of those who had lost out in fractional infighting.

Asked about the allegations, Mr Kelly said "I was happy that the Labour Party offered to assist the CLP in this matter and I look forward to the report back to the CLP.

"Understandably, a number of colleagues were unhappy at the radical but necessary changes within the Council, however our number one priority must be to our local communities."

Brian Roy, in a response to Mr McKay's letter, also seen by The Herald, offers to mediate between the two sides in the North Lanarkshire party. Mr Roy said he had already verbally assured the new chairwoman of the CLP that he was "confident that one all expenditure and income was reconciled...that the accounts would be accepted".

The local party, however, had not been able to pay affiliation fees to the national party, Mr Roy confirmed. The CLP, he said, had therefore agreed to forego payments it would have expected to receive from HQ to make up the shortfall.