An investigation has been launched into why money earmarked for cycling projects across the State has not been invested.

The WA Budget papers reveal a $10 million "underspend" for initiatives under the State Government's much-vaunted Bicycle Network Plan.

It mostly involves money set aside for six major metropolitan bike paths.

Of the $9.16 million allocated to the paths, only $1 million has been spent - a shortfall Transport Minister Troy Buswell has blamed on "planning delays".

And only half the $3.5 million allocated to the metropolitan and regional local government grants programs in 2012-13 has been spent.

According to a spokesman for Mr Buswell, this has prompted the Department of Transport to begin "a thorough review" of the program.

Discussions between the department and local authorities would begin soon, he said. It is understood the talks will consider options to make the program more attractive and easier for councils to apply for money.

One stumbling block may have been the requirement for councils to match the funding dollar-for-dollar.

Bicycling WA chief executive Jeremey Murray said the "substantial underspend" was not that surprising given the extensive planning required to build paths and the lack of State Government funding for bike riding in previous years.

"My understanding is that a lot of planning and design work has been carried out but not a lot of tarmac has been put on the ground," he said.

On top of the $20 million provided in 2012-13, the Government has provided $15 million to further develop and improve cycling infrastructure.

The Budget papers said active transport, particularly cycling, needed to be continually promoted as a viable alternative for transport over short distances.

The six paths being funded are from the Narrows Bridge to Mt Henry Bridge along Kwinana Freeway, Cranford Avenue to South Street along Kwinana Freeway, Glendalough to Balcatta on Mitchell Freeway, Burswood to William Street along the Perth-Armadale rail line, Bassendean to Midland along the Perth-Midland rail line, and Shenton Park to Loch Street and Grant Street to the Beehive Montessori School along the Perth-Fremantle rail line.