The new surface will replace the present dust path

L�n Eifion stretches from Caernarfon along the old railway line to the village of Bryncir.

The refurbishment will mean closing a 2.4 mile (4 km) stretch between Caernarfon and Dinas as tarmac is laid down instead of the present dust surface.

Work is expected to last until at least the end of February.

"Figures from last year show this cycle track is hugely popular and a counter just outside Caernarfon recorded 55,000 walkers and 6,000 cyclists," said Mark Balaam, Gwynedd Council's countryside warden.

The new surface would make the path easier to use, Mr Balaam added.

"Although this essential work will cause some inconvenience to users, which we apologise for, we hope the new surface will mean that even more walkers and cyclists make use of L�n Eifion," he added.

L�n Eifion is part of L�n Las Cymru, and route number eight on the National Cycle Network, which runs from Holyhead on Anglesey to Cardiff.

Throughout Gwynedd there are over 31 miles (50.5 km) on the Lonydd Glas (recreational routes), mostly established on or near disused railway lines.

"We are very lucky to have these routes as many are set away from present roads but still pass through many communities," Mr Balaam added.

Sustainable transport charity Sustrans features L�n Eifion as an easy/moderate route on its website, calling it a "scenic route".