LONDON (AP) — Britain’s Conservative government is set to approve a contentious, expensive plan for a high-speed rail line linking London with central and northern England, despite opposition from environmentalists and even some members of the governing party.

Prime Minister Boris Johnson is making an announcement Tuesday about the project, known as High Speed 2 or HS2. British media reported that he would give it the go-ahead.

The first 140-mile (225-kilometer) stretch of the line will link London to Birmingham, England's second-largest city, with trains traveling up to 225 miles an hour (360 kph). A planned Y-shaped second section will then extend to the northern cities of Manchester and Leeds.

First approved a decade ago, the project has been the subject of repeated delays and reviews.

Opponents claim the plan is too expensive and will ruin tracts of picturesque countryside. The projected cost, estimated at 33 billion pounds in 2011, has soared to more than 100 billion pounds ($130 billion).

Conservative lawmaker Michael Fabricant, who represents a central England district on the HS2 route, said the rail line would damage or destroy 100 ancient woodlands, causing “immense” environmental damage.

Johnson, who won a large parliamentary majority in December’s election, has promised to build major new infrastructure projects t o better connect parts of the U.K. in the wake of Britain's divisive exit from the European Union. He also has vowed to boost regions outside the London-dominated economic hub in southeastern England.

Britain has an extensive but antiquated rail system that relies heavily on Victorian infrastructure. HS2 would be the first new railway built north of London for more than a century.

Britain lags behind European countries such as France and Spain when it comes to high-speed rail. Its only existing high-speed line is High Speed 1, completed in 2007, which links London to the European mainland via the tunnel under the English Channel.

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