The Welsh Government has started searching for a contractor to design and build a new 23km motorway in South Wales.

Originally proposed in 1991, the £800m scheme was dropped by the government in 2009 due to an increase in costs.

In order to tackle local congestion on the M4 relief road, the government plans to build a new stretch of motorway to the south of Newport.

The existing M4 between Magor and Castleton will also be reclassified as a non-motorway.

"Originally proposed in 1991, the £800m scheme was dropped by the government in 2009 due to an increase in costs."

An additional new connection between the M4, the M48 and the B4245 is expected to provide relief to Junction 23A, as well as the local road network.

The aim of the new contract is to publish draft orders in spring 2016, with plans to hold a public inquiry by 2017 and begin construction by mid-2018.

The motorway construction is slated for completion during late 2021 with the overall project scheduled to be completed by mid-2022.

Initially, the Welsh Office proposed the M4 relief road between Magor and Castleton in 1991, but in the following years there was little progress on the scheme.

In March 2003, plans for the new motorway were announced as part of a series of measures to improve road transport in Wales.

Expected to cost between £350m and £1bn, the road would be financed by a private finance initiative with the Welsh Assembly and was planned to be the second full toll-paying motorway next to the M6 Toll in the UK.