Scotland Transerv said specialists were working "flat out to find an engineering solution".

A spokesman said debris may be removed from the road between the A814 at Arrochar and the B828 by a "controlled landslip" using water.

Work could start on Monday though it is not known when the road will reopen.

The spokesman added: "The hillside is still unstable, experts are on site trying to find a solution.

"We need to address erosion to the road and remove debris.

"Work is ongoing and until that is completed we can't say when the road will reopen."

The road was closed after 400 tons of soil and rock, loosened by several months of rainfall, tumbled down onto the road overnight on Sunday.

This situation ... is intolerable and must be sorted out as soon as possible Jamie McGrigor MSP

Jamie McGrigor, MSP for Highlands and Islands, said the A83 was a lifeline route.

In a letter to the Transport Minister Stewart Stevenson, he said: "The closure is costing businesses a fortune, especially hauliers forced to take lengthy diversions.

"This situation on two major roads leading into Argyll being reduced to crawler traffic in parts is intolerable and must be sorted out as soon as possible.

"It is Transport Scotland and the Scottish Executive who must now take immediate action."

Chris Clark, co-owner of The George Hotel in Inverary, said the closure was hitting passing trade.

"It's traditionally a very quiet period of year," he said.

"This adds an extra angle, our takings are going to be down even more.

'We understand'

"It's very difficult for everyone in the town.

"Lunches have suffered badly, we benefit from daytrips and they're just not coming. It's a nightmare for everyone."

He added: "Most of the businesses in the town can absorb the costs."

A spokesman for the Scottish Government said: "We understand the concerns of businesses and the crucial importance of the road for the area.