Lorries will be allowed to go faster on the A9 to improve the safety and operation of the road, the Transport Minister has announced.

The speed limit for heavy goods vehicles (HGVs) on the road will increase from 40mph to 50mph, Keith Brown said.

"I am announcing a plan for a 50mph HGV speed-limit trial to be introduced at the same time as the average speed cameras. Currently, HGVs over 7.5 tonnes are allowed to travel at 40mph on single carriageway sections of the A9," he said.

"The trial, which aims to improve the operational performance of the route, will go ahead alongside a safe driving campaign run by the haulage industry and the A9 Safety Group.

"This is a measure that is being brought forward to address complex safety and operational issues that we face on the A9. The speed limits for all other categories of vehicles will remain the same.

"The trial, which will last 36 months, will involve quarterly monitoring assessments and evaluations of performance.

"The A9 remains one of Scotland's most important links and this pilot is just one of many engineering, enforcement and education measures being introduced to improve the safety and operation of the route ahead of full dualling.

He added: "Before the trial can commence, regulations must be taken through parliament and average-speed camera technology procured and installed. The earliest opportunity to undertake this preparatory work and commence the trial could be spring 2014.

"We would certainly wish to have this started during next year, albeit we recognise there are important events, such as the Commonwealth Games and Ryder Cup, which must be taken into account."

The Road Haulage Association in Scotland welcomed the announcement.

Director Phil Flanders said: "We anticipate a smoother flow of traffic and a substantial reduction to the frustration among car drivers that the low speed limit creates.

"Many motorists have been unable to understand why HGVs travel at a speed that held them up so unnecessarily. That is why some trucks have had stickers pointing to the legal limit.

"The great majority of HGVs are driven in an exemplary manner. The focus on HGVs is a good time to stress to the industry that we should be working to eliminate the instances of bad or inconsiderate driving that let the industry down.

"One example is taking too long to overtake another HGV on dual carriageways and two-lane motorways, so holding up motorists.

"Another, far worse, is the aggressive tailgating of motorists. Such behaviour is rare but it should not happen at all. It is dangerous and even if an accident does not occur, it causes fear and stress to the car driver. It is inexcusable and the industry can do much to put an end to the practice."

Conservative Mid Scotland and Fife MSP Murdo Fraser, who heads the Dual the A9 campaign, said: "The Dual the A9 campaign has been inundated with messages from road users calling for an increase in HGV speed limits and I have been lobbying the transport minister for some time.

"The deadly reputation of the A9 is built on its confusing layout and accidents being caused by frustrated drivers overtaking slow-moving goods vehicles. Hopefully some of that can be neutralised by this move.

"However, the Scottish Government must not allow these temporary measures to deflect from the dualling project and must remain committed to the fastest possible dualling timetable."

Highland Council leader Drew Hendry said: "Increasing the speed limit will reduce the potential of hold-ups and driver frustration on our roads. We also welcome the fact that this will be run on a trial basis to ensure that it is evidenced to improve safety."