A landslip at the Rest and Be Thankful in Argyll and Bute yesterday left motorists facing a 50-mile detour by road or ferry journey between Dunoon and Gourock as between 100 and 150 tonnes of mud and earth fell on the A83 after being dislodged from the hillside by heavy rain.

The road was officially closed at 7.14am and reopened to vehicles at 3pm after an intensive clean up operation. But the disruption was condemned by Argyll and Bute Council leader Roddy McCuish who said he was "hugely disappointed" that an emergency relief road due to have been open by now was still undergoing work.

The A83 has been closed six times in the last five years by landslips, with the latest occurring at a similar point to the previous two, between Ardgartan village on the shore of Loch Long and the Rest and Be Thankful car park.

"I am hugely disappointed. We were promised by the Scottish Government the temporary alternative route would be in place by November and that has not happened. It has now been promised this will be in place by the end of January but how many more times will Argyll and Bute be effectively cut off before then?" Mr McCuish asked.

"We need a permanent fail safe solution to keep the A83 open at the Rest and Be Thankful so Argyll and Bute can carry on as normal even when bad weather hits the area. Our businesses and people suffer every time the main route into Argyll and Bute is closed."

A spokesman for Transport Scotland said there had been a "speedy" clean up operation. "We are acutely aware of the views of the communities across Argyll to keep the A83 open for business – our absolute priority is always the safety of motorists and we are grateful for their patience," he said.