A GAP in a railway line fence needs to be blocked off as soon as possible to stop children from running across the tracks during the holidays, a councillor warns.

Councillor James Harris and Monmouthshire Council have called for Network Rail to fix a gap in a fence at Mill Reen in Undy, which they say is being used by children to walk across the tracks.

The company has placed a temporary mesh fence on the site, but Cllr Harris said a large gap remains.

Network Rail told Monmouthshire Council, which has advised the Health and Safety Executive of the situation, that it can not install a permanent fence until March 13.

Councillor Harris told the Argus the fencing usually stops people from accessing the railway line, which carries high speed traffic to the Severn Tunnel.

He’s worried the site is an accident waiting to happen over the school holidays.

“It’s wrong, March is a fair old length of time to wait to have this sorted,” he said.

He said the mesh, installed by Network Rail last week, only covers the culvert and that the railway tracks are still accessible from either side.

A spokeswoman said the council raised concerns about the delay in light of the school holidays, and said there is clear evidence the area is being accessed by children.

“We’ve advised the HSE of the situation and we have contacted Network Rail on a number of occasions to bring the date forward,” she said.

A Network Rail spokeswoman said a temporary fence has been installed at the location, while a survey of the area is also taking place before a permanent fence is installed.

"Those who have witnessed any trespassers and vandals in the act are encouraged to ring the transport police," she said.