A group of Bristol children had to walk more than five miles because there was no room for them on their school bus.

Becca Connor and Abigail and Tyler Johnston, from Lawrence Weston, trekked over the Avonmouth footbridge alongside the M5 and walked up through Pill.

They had almost reached St Katherine's School in Ham Green when they were picked up by their head teacher Stephanie Quayle.

"She thought at first they were bunking off," said Becca's mum Lin Connor. Now Mrs Connor and other parents are having to take time off work and rearrange their shifts to take the children to school by car until the problems are resolved.

Simon Johnston, father of Abigail, 13, and Tyler, 12, said: "It is a nuisance, but I need to know my children are safe."

St Katherine's business manager Laurence Frewin said urgent talks were being held with the bus operators to find a solution.

Mr Frewin said: "We can understand the parents' anxiety. We are looking at alternative arrangements to safeguard the students' welfare."

Bus firm Eurotaxis said it would alter its routes to ensure that all buses passed the busiest stops but this could not be done immediately because notice had to be given and procedures followed.

Mr Johnston, 37, of Badenham Grove, said: "Many parents like myself are working full time and rely on the bus service. The operator has a responsibility to get our children to school safely."

Mrs Connor, 45, a care worker, whose son Mark, 15, cycles to St Katherine's, said that after failing to get on the bus at Long Cross, Becca, 13, and her pals had run to another stop by the Hope and Anchor pub, but all three buses had gone.

The walk took them more than an hour before Ms Quayle found them.

Hundreds of children from Bristol travel by bus to the North Somerset secondary school every day, paying £3 for a return ticket.

The service is provided on a commercial basis and is not commissioned by the school, the city council or North Somerset Council. Lawrence Weston and Shirehampton are some of the last stops on the route before the bus takes the motorway bridge over the river.

Eurotaxis was last year running five services to the school, but has had to stop two of them because of restrictions placed on the operator by the Traffic Commissioner.

Nailsea firm North Somerset Coaches has taken over one route but the loss of the other has meant high demand for places on the remaining three 106-seater double-deckers.

William Sanzo, a manager at Eurotaxis, said the problem had been made worse because one of the company's buses was off the road and had had to be replaced temporarily by an 88-seater. We would like to put on an extra bus to run behind the other three and pick up any children who are left over, but we are not allowed to.

"We are doing everything we can by using the largest double- deckers you can get. Our drivers issue the right number of tickets for the number of seats on the bus, to make sure we never overload," he said.

Traffic Commissioner Sarah Bell earlier this month refused Eurotaxis' appeal to be allowed to run more than 11 services at any one time.

She strongly criticised the firm, saying that after being called to three public inquiries since 2005 it should have been making stringent efforts to ensure that it was complying with licensing arrangements and not running illegal services carrying school children.