Danish MPs have given the green light to the construction of the Fehmarnbelt underwater tunnel which will reduce travel time between the country and Germany to just a few minutes.

Work on the Danish side is now expected to start on January 1, 2021, and the tunnel — known as the Fehmarnbelt link — is now forecast to open in mid-2029, the Ministry of Transport said in a statement on Friday.

Transport Minister Benny Engelbrecht hailed the MPs agreement as a "historic decision", describing the tunnel as "a new gateway to Europe".

The 18-kilometre tunnel will link northern Germany to the Danish island of Lolland which are separated by the Fehmarn Belt — a strait in the western part of the Baltic Sea.

Construction was postponed by six months because of the COVID-19 pandemic.

The 52.6 billion Danish kroner (€7 billion) project will feature an electrified double-track railway and a four-lane motorway. It will allow trains and cars to cross the strait in just seven and ten minutes respectively. At the moment, a ferry takes about an hour to make the crossing.

The Fehmarnbelt link will be built as an immersed tunnel. First, a 60-metre wide, 16-metre deep, trench will be dug up in the seabed, into which hollow concrete elements, cast on land, will be placed.

The concrete elements will each weigh 73,000 tonnes and will be towed by large tugboats before being lowered down.

The Fehmarnbelt link will be the longest tunnel of its kind anywhere in the world.

Construction on the German side is, however, not expected to start until mid-2022.