A road which Welsh Government spent £26 million on has suffered flooding just weeks after opening.

The new route of the A4226 between the A48 and Barry was officially opened on October 15 to make it easier for motorists to get to and from Cardiff Airport.

But the road – known locally as Five Mile Lane – was open a matter of weeks before parts of it was flooded when heavy rain hit the Vale of Glamorgan last weekend (November 2 and 3).

The Local Democracy Reporting Service has been told up to a foot of standing water was on the road in some places, including the lay-by near the Welsh Hawking Centre.

Campaigners are now criticising the design and drainage of the new road – with some locals dubbing the route "Five Mile Canal".

The council said the flooding affected the older parts of the road and occurred due to fly-tipping in the drainage system.

Ian Perry, from St Nicholas with Bonvilston Community Council, said the new Five Mile Lane was built on the cheap with many of the active travel routes have been downgraded.

He said sections of the foot and cycle paths along the road have been either narrowed or shortened or offer no protection from vehicles travelling up to 60mph.

Mr Perry said: "They put saving money ahead of safety and the needs of the public. There are design faults all over the place.

"Every time it rains there are water issues. They knew about these problems before because it had been reported.

"It was purely about the car. They wanted to do it on the cheap."

The £25.8million route between Sycamore Cross and the A48 and the Weycock Cross roundabout in Barry was funded by Welsh Government and managed jointly with the Vale of Glamorgan Council.

Cllr Vincent Bailey, leader of the Conservatives on the Vale of Glamorgan Council, said: "Having spent £26 million upgrading Five Mile Lane, it's rather worrying that it seems to have become badly flooded at the first sign of heavy rain.

"It's not as though this kind of weather is unusual in Wales, after all.

"These improvements were made to boost safety and to improve connectivity, so the council and Welsh Government will be hoping that this isn't a recurring problem with the way the road was built.

"Otherwise, it's not going to provide much of an economic boost for the region if the new Five Mile Lane is forced to close every time it rains."

Welsh Government and Vale of Glamorgan Council said the new road will lead to shorter journey times and improve safety. The old Five Mile Lane was an accident black spot.

Along with the new foot and cycleways a bridleway and bridge have also been built to provide a crossing for horse riders.

A Vale of Glamorgan Council spokesman said: "The flooding on Five Mile Lane affected the original road not the new section and, while the level of rainfall last Saturday was a contributing factor, it occurred because the drainage system became blocked with fly-tipped material.

"Further investigation work into the incident is under way and any improvements necessary to reduce the risk of flooding along this section of highway will be undertaken."

A Welsh Government spokesman said: "We are working with Vale of Glamorgan Council to find out why flooding occurred on sections on the road and have asked them for an urgent update."