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About 10% of Wales' roads covering 1,932 miles are in a poor condition, according to BBC data.

Defects such as bumpiness and surface cracks were measured over six years using Welsh Government statistics.

Over that period, Powys had an average 19.6% of its network in a poor condition and Flintshire 5%.

A Welsh Government spokesman said it looks after trunk roads with local authorities deciding how to treat subsidiary routes.

Over the six year period until 2016-17, the worst averages were Powys (19.6%), Ceredigion (14.7%), Wrexham (14.2%), Carmarthenshire (13.4%) and Pembrokeshire (10.2%).

Those local authority areas with the lowest were Flintshire (5%), Swansea, Neath Port Talbot and Torfaen (6.1%) and Merthyr Tydfil (6.8%).

Statistics came from the Welsh Government's data unit's local authority performance measures over six years, while Department of Transport information was also gained looking at England's roads over eight years.

Halton (1%) and Telford and Wrekin (1.3%) had the lowest and City of London (15.3%) the highest numbers of A roads in poor condition.

A Welsh Local Government Association spokesman said roads are exposed to a range of challenging weather conditions - such as the freeze-thaw process in winter, which creates potholes.

He said: "If these are not addressed, then they gradually become worse.

"Local authorities' ability to address this has been reduced as a result of ongoing budget cuts."

While he praised a Welsh Government borrowing initiative that saw £170m invested in the network over three years, he said such investments need to be sustained.

"The Welsh Government has responsibility for the trunk road network in Wales, which is regularly inspected and any safety related defects addressed," a Welsh Government spokesman said.

"It is for local authorities to determine how best to ensure subsidiary roads remain in the best possible condition."

He pointed to an announcement in February that £30m will be given to improve the state of roads in Wales.