Bristol's primary school places crisis has been described as a "shameful episode" for the city council by a member of its ruling cabinet.

Councillor Gary Hopkins said the situation in which hundreds of families had to wait an extra three months to be allocated a school place was shocking.

A difficult situation had been made worse because of the decision last year not to go ahead with a new primary school in Bishopston, he said.

"Those responsible for the cancellation of that school should hang their heads in shame," he said, in a jibe at the previous Labour administration.

The Liberal Democrats gave the go-ahead for the Bishopston school when they were last in control of the council but the decision was reversed in January 2008, while Labour was running the authority.

It said expanding the neighbouring Sefton Park schools was a better option.

Councillor Bev Knott, who represents Bishopston, said the area's increasing population of families with children had been evident for 10 to 15 years.

Yet a citywide review of primary schools last year had failed to address the issue, he said.

The Lib Dems reassumed control of the council in February and quickly revived the plan for the 210-place Bishopston school.

Last night, the cabinet formally gave the go-ahead for it to be built – and the aim is for it to be finished in time for the start of the school year in September 2010.

Councillor Clare Campion-Smith, cabinet councillor for children, said there were advantages and disadvantages to both the Sefton Park expansion and the Bishopston plan, but the new-build school would be more likely to provide much-needed places quickly.

She said: "It is a constrained site. Clearly it would be much better if we could build a two-form entry school."

Mrs Campion-Smith said discussions would have to be held with representatives of City of Bristol College and with Gloucestershire County Cricket Club, which are both close to the school site.

She said: "We have got to press on with this quickly.

"The problems can be solved.

"It will require determination. I think we are going to deliver a good school for the people of Bristol."

A report to the cabinet meeting outlined the 12 schools where 236 extra reception places are to be provided for September.

As the cabinet was being held, governors at another school were meeting to discuss providing an additional 30 places, which could mean some children can be made new offers of places closer to their homes.