A new high-speed rail line linking two cities in Portugal is a step closer to becoming a reality with an initial tender seeking £1.7billion of investment.

Portugal’s rail infrastructure management firm, Infraestruturas de Portugal, will use the billions for the first phase of the scheme, linking Porto to Soure along the line which would ultimately link to Lisbon.

A 43-mile long (70km) Porto to Oiã section of the line features 7.2 miles (11.6km) of tunnel, 5.9 miles (9.5km) of bridges and 1.7 miles (2.8km) of viaducts, according to online trade magazine, Railway Technology.

The publication says the release of the tender marks "one of the biggest steps" towards the start of the project, which is expected to commence in 2025.

Work is set to begin on a second phase between Soure and Carregado in 2027 with a final stretch coming after 2030.

Former Portuguese Prime Minister António Costa said: "This project corresponds to a vision of our country, our development strategy and our insertion in the European continent.

"We have to have a country that is both competitive externally and that is more cohesive internally."

Once complete, the 180 mile (290km) line will link Portugal's two biggest cities and cut the travel time down to 75 minutes from two hours and 49 minutes.

IP expects passenger numbers to be boosted by 10 million more per year than those seen on an existing line.

The track is to be built on an Iberian gauge of 1,668mm so that trains can link to existing tracks and those in Spain.