Sarah Boyack: "Deeply unfortunate"

The executive will now have to use the Scottish Parliament's fast-track procedures to initiate legislation to allow the tolls - 60p for cars - to be reinstated.

The new law will be backdated until July but until it comes into force no charges can be levied on the bridge, which opened in 1971.

The original order to collect tolls was granted for 20 years, but it was later decided to give ministers powers to continue tolling for periods of five years at a time.

Although Ms Boyack gave permission for an extension to the toll levy, "an administrative error" meant the necessary order was not laid before the Scottish Parliament.

Ms Boyack said: "This error is deeply unfortunate. It should not have happened."

Suspended immediately

"The legislation we propose will rectify the position from 2 July. In the meantime I have ordered tolls to be suspended immediately."

The minister said that she had asked the head of the transport department to investigate the circumstances surrounding the mistake and make recommendations how best to avoid the situation occurring again.

An executive spokesman added that it was "very rare" for administrative oversights of this nature to occur but the toll suspension was likely to continue for "a matter of weeks".

The toll suspension has been seized upon by the SNP who branded the oversight as "a stunning act of incompetence".

Andrew Wilson: "A total mess"

The party's transport spokesman, Andrew Wilson, said: "If the government cannot even run Scotland's bridges - which is a matter of simple administration - how can they be trusted to run the rest of Scotland properly?

"The question also arises that if the government have been charging motorists illegally would motorists be able to claim compensation."

Mr Wilson said the situation was "a total mess" and accused Ms Boyack off "taking her eye off the ball".

Almost 8 million vehicles a year cross the Erskine Bridge and it takes about �5m in tolls annually.

Neil Grieg of the AA said he found the incident "totally amazing".

Standard practice

He said: "We were actually aware that there was a renewal of the tolls coming up. In fact, West Dunbartonshire Council were using it as an opportunity to co-ordinate a major campaign to get the tolls taken off.

"So if external organisations were aware this was happening then surely the executive themselves must have been aware. This should just be standard practice."

Mr Grieg calculated that more than �800,000 had been taken from motorists illegally during the two months since the licence expired.

He said: "I would have thought that rather than fast-tracking legislation through the Scottish Parliament a better gesture would have been to give drivers two months free from tolls."

Danny McCafferty from West Dunbartonshire Council said the blunder could be a "golden opportunity" to abolish toll charges.

He said: "West Dunbartonshire has a very ambitious riverside plan to bring 6,000 jobs over the next 10 years to our side of the river, and the scrapping of the toll charges would aid that development."