Scottish National Party leader John Swinney has asked the Electoral Commission to investigate donations to the first minister's constituency party.

Mr Swinney claimed that Jack McConnell's reputation had been left "in tatters" by the funding row.

His comments came as the local Labour Party in Mr McConnell's Motherwell and Wishaw constituency admitted that it had failed to declare a second batch of donations.

This followed the revelation on Tuesday that the Motherwell and Wishaw Labour Party had breached the law by failing to declare union donations.

John Swinney: "A full, independent inquiry"

Mr McConnell conceded that it was "shocking" that the money had not been declared.

The Electoral Commission has signalled its intention to contact Labour about the claims that donations from the Iron and Steel Trades Confederation (ISTC) to a development fund were not declared.

The latest disclosure concerns cash collected at a fund-raising dinner for the Motherwell and Wishaw constituency party which should have been declared to the Electoral Commission in July but was not.

A Labour Party spokesman admitted that there had been "a mistake" over declaring funds from the dinner event.

Breach of rules

He added: "I don't know why it wasn't. There was just a delay in working out what had to be declared."

The dinner, held at the Dalziel Golf and Country Club near Motherwell in March, was attended by Northern Ireland Secretary John Reid, Mr McConnell and Labour MP Frank Roy.

The development came after party chiefs admitted they had not declared payments from the ISTC of �375 a quarter in breach of rules on donations to political parties.

The cash was paid into the controversial development fund from which �200 was used in Mr McConnell's leadership bid following the death of Donald Dewar two years ago.

Jack McConnell's reputation is now in tatters and he has to act now if he is to preserve the integrity of his office

SNP leader John Swinney

The SNP leader has now written to the commission's chairman Sam Younger asking him to instigate an investigation into "various irregularities".

"Jack McConnell's reputation is now in tatters and he has to act now if he is to preserve the integrity of his office," said Mr Swinney.

He said the first minister had to co-operate with any Electoral Commission investigation and bring in the police if he suspected any criminal wrongdoing.

Mr Swinney also called on Mr McConnell to hand over the books concerned to an independent auditor.

Labour launched an inquiry last week when it emerged that a local activist may have used party funds without authorisation.

It was suggested that there may be an �11,000 black hole in the constituency accounts.

The accounts are held at the North Lanarkshire Municipal Bank, which is backed by the local council.