Drivers using Oxford's Southern Bypass have demanded action from highways managers after repeatedly getting caught in rush-hour traffic.

Commuters who were delayed for more than an hour last week between the Rose Hill and Hinksey Hill roundabouts on the city's ring road called the county council's highways department for an explanation.

The council pinpointed traffic lights at Hinksey Hill roundabout as the problem, and the Highways Agency, which is responsible for it, sent out an engineer to carry out repairs.

Hugh Blaza, 52, from South End, Garsington, who works as a commercial solicitor in Witney, was one of the drivers stuck in the jam.

He said: "For the past few weeks there have been unexplained hold-ups on the Southern Bypass. On at least two mornings a week, the traffic backs up and it adds about an hour to your journey, while on other mornings the same journey takes about five minutes. It's strange because there aren't any accidents or roadworks which would explain the delays.

"I contacted the county council and received a letter from them which suggested a number of long-term plans for reducing congestion on the network, including new park-and-rides, which is all very admirable, but I want this to be fixed quicker than that.

"At the moment, I'm missing morning meetings and other engagements because of this."

Tim Atkinson, who works for the county council's traffic control team, said the council had received at least three calls from irate drivers stuck in traffic.

He added: "On Wednesday morning, the problems were awful. We pinpointed the Hinksey Hill interchange as the source of the hold-ups.

"That roundabout is controlled by the Highways Agency from their base in Hampshire and we are talking to them to see if there is a problem with the sequencing of the lights.

"Work is also being carried out on the Northern Bypass, at the Green Road roundabout, and that could be causing some displacement of traffic on to the Southern Bypass."

In April 2003, the A423 between the Hinksey Hill and Abingdon Road interchanges was "detrunked" and control of the road was handed to the council.

But the Highways Agency, which controls motorways and other major routes, refused to hand over control of the Hinksey Hill traffic signals because it wanted to guarantee the flow of traffic from slip roads on to the A34.

The lights had broken down on numerous occasions, including during the morning rush-hour.

Highways Agency spokesman Martin Dellar said: "After problems with the lights were reported on Wednesday, we sent an engineer out, and he adjusted the sequencing.

"Since then there have not been any complaints, and we would like to apologise to the drivers who suffered delays."