Town hall planning officers have been slammed after a series of blunders left the council thousands of pounds out of pocket.

It has emerged that permission was granted in error for two applications: one after officers failed to recognise planning permission was required for a roof extension and the second to a council worker's property within a conservation area.

The council will now be forced to repay £3,100 and £500 to the complainants of the cases dating back to December 2007 and October 2008 and may be ordered to pay a further compensation payout.

Labour leader Julian Bell said it was disappointing that it had taken such a long time for the issue to come to light and showed the level of inefficiency in the planning department.

Councillor Bell said: "There are clearly real problems with both cases; it is not right that residents should go to such a level of complaint to the ombudsman to get justice and fairness, and this reflects badly within the planning department. It shows a non-responsiveness to local residents' legitimate expectations of the planning service and this is very disappointing.

"Hopefully now this has come to light there will be a culture of openness to ensure this maladministration won't happen again and customer services can be improved."

The ombudsman report also advised a review of the planning services to improve procedures and train officers to ensure this will not happen in the future.

Pat Hayes, executive director of regeneration and housing, said the department would do everything to prevent a planning service breach.

Mr Hayes said: "These are very serious cases and they do underlie problems within the planning service.

"We need to change the culture in which individual officers take responsibility and acknowledge when mistakes are made in order to improve relations with customers.

"We will tackle this head-on to deliver a service for the 21st Century and not the 19th Century.

"Investigating development applications is always difficult and a complex area which needs to be undertaken properly and although this took place some years ago, we will be careful to train officers and prevent a further planning breach."

Council leader Jason Stacey said: "All officers make mistakes but we need to acknowledge when we make mistakes rather than the issue going to the ombudsman.

"Both these cases are embarrassing to the council and I don't want to see cases like this again."