Sections of the planned Aberdeen bypass could open in stages ahead of the estimated completion date, the Transport Minister has said.

Keith Brown said there can be no cast-iron guarantee about timescale but that benefits of the £653 million road could be felt before spring 2018.

The pace of progress on the Aberdeen Western Peripheral Route (AWPR) has been criticised and the scheme itself was snarled up in a lengthy court battle.

Mr Brown focused on the project as a key part of the coming year, expanding on earlier comments about staged progress along the 28-mile route.

"By summer, we expect to be in a position to announce the preferred bidder who will build the new road," he said.

"Once they have been selected, we will then be in a position to look at what refinements can be made to the delivery programme for specific elements.

"There is no cast-iron guarantee I can give at this stage, but we will do everything we can to work with the preferred bidder to see what can be done without compromising the project completion date of Spring 2018 or produce unnecessary disruption or congestion.

"Where possible, this could mean sections of the new road opening earlier than the completion date."

Transport Scotland, the government agency behind the scheme, has been lobbied by Aberdeen airport, the city harbour and communities, asking for speedy construction of individual sections. One proposal is to improve access to the airport at Dyce to the north of the city before the completion date.

The project was given the go-ahead in 2012 but has been on the drawing board in some form for years before that.

Mr Brown said: "Since coming to power in 2007, the Scottish Government has done everything we can to redress that neglect and push forward major transport investment and improvements in the north east. The AWPR is key to this - it will deliver over £6 billion of investment to the north-east over the next 30 years."