A "urgent" investigation into how Barnet Borough Council made errors in the way its committee members were appointed is to be held.

Last night’s assets regeneration and growth committee meeting descended into chaos as councillors were told the allocation of seats had been “flawed” and “invalid”.

The ruling Tory group appointed councillors to committees following last month's elections, but an error meant they were incorrectly calculated.

The authority announced it was changing the way it makes decisions from a cabinet to committee system before the elections, but new committees cannot be reconstituted until the next full council meeting of July 15.

Andrew Travers, the authority’s chief executive, said an external reviewer will conduct an urgent investigation, which will be published at the earliest opportunity.

Speaking during yesterday’s meeting, Mr Travers said all decisions taken since the May election are invalid, and no committee could make any binding decisions until the next full council meeting on July 15.

However, he later corrected himself to say he was consulting with party leaders over whether they could still take place.

Although barrister James Gaudie has since confirmed the proportionality report was flawed, he believes decisions taken during this time “would be valid”.

However, Mr Travers said: “I do not think that this would provide a clear and transparent basis for sound decision-making, and have concluded that meetings should be postponed pending matters being rectified at the meeting of full council scheduled for 15 July.

“The current position is deeply regrettable and I apologise sincerely to all members. The move to committee system was always going to be challenging but the change has not been implemented as efficiently as members, or indeed residents, should expect from the council.

“It is important that there is a clear understanding of how this situation has arisen and what action, if any, should be taken.

“I will be appointing an external reviewer to conduct an urgent investigation into the processes leading to the reports presented to annual council on 2 June. This will be published at the earliest opportunity.”