A MSP has urged lorry drivers campaigning for higher speed limits on the A9 not to blockade the road north to Inverness over Christmas.
Labour’s Dave Stewart believes a go-slow from Perth will lead to driver frustration, which could cause accidents.
Council leaders in the Highlands and Perth and Kinross have joined lorry drivers campaigning for an increase in the speed limit on single-carriageway stretches of the A9 from 40mph to 50mph for commercial vehicles over 7.5tonnes.
Lorry drivers want the limit raised before the introduction this summer of average speed cameras.
Earlier this week, protest organiser Conor McKenna announced that he and other fed up HGV drivers would stick rigidly to the official speed limit throughout December.
Highland MSP Mr Stewart, who launched the 50mph campaign with Mr McKenna – said he was not suggesting lorry drivers should break the speed limit.
But he added: “I would urge them not to convoy down the A9 as this could lead to driver frustration for other road users and the very people we are trying to help.
“I would ask lorry drivers to leave plenty of space between themselves and other HGVs, and when queues build up behind them to pull over and let faster vehicles pass when possible.
“The fact is that frustration kills, and on the A9 frustration, in particular, is a contributory factor in many collisions.”
Mr Stewart has lodged a question in an effort to prompt Transport Minister Keith Brown to increase the speed limit.
Mr McKenna said convoying by lorries was “inevitable” if drivers stick to the speed limit.
“That is what we are trying to highlight – that when the average speed cameras come in it will be an even more dangerous route – but no one seems to be paying attention.”
Highland Council leader Drew Hendry has written to Mr Brown, on behalf of the local authorities, backing a 50mph limit for lorries and suggesting a possible lower speed limit at accident blackspots.
He said: “The leaders are agreed in their support for the increase of the speed limit on single carriageway stretches of the A9 for these vehicles.
“We feel this would be appropriate and reduce driver frustration caused by these slow-moving vehicles.”