The SNP government has been warned that “pandering” to the Scottish Greens by not completing key road improvements will cost lives and damage the economy.

Scottish Conservatives will increase recent pressure on SNP ministers to spell out a timetable for completing the dualling of the A9 between Perth and Inverness and the A96 between Inverness and Aberdeen.

The SNP stated in its 2021 manifesto: “We were the first Government to commit to dualling both the A9 and A96 and remain committed to completing both programmes, ensuring the road network between all Scottish cities is of dual carriageway standard.”

However, there is growing frustration among users of the route and opposition politicians at the slow progress.

Shadow Transport Minister Graham Simpson, who will lead a debate in parliament on Wednesday, says the Greens’ opposition to road-building is a contributory factor.

He said: “The tragic spike in fatal collisions on the A9 and A96 this year is horrific – and highlights the need for action from the Scottish Government now.

“SNP ministers must stop pandering to their anti-car coalition partners – the Scottish Greens – and get on with delivering these crucial, life-saving upgrades now.

“While saving lives is the paramount consideration here, these upgrades would also boost Scotland’s economy.”

Fergus Ewing, a former SNP minister, criticised his own party for failing to address concerns over failures to dual the roads.

Government agency Transport Scotland says it has carried out a number of improvements at one crash site to reduce the frequency of accidents.