The UK government on Thursday announced a two-year delay to construction on part of the HS2 high-speed railway connecting London with cities in the north of England.

The part of the line running into central London would also be delayed, as part of cost-saving measures, Transport Minister Mark Harper said.

The project, which is being built in stages, is set to cost more than £100 billion funded mostly by the state and will take years to build.

Former prime minister Boris Johnson heralded HS2 as a key infrastructure project aimed at helping drive Britain's post-Brexit economy.

Johnson however was forced to scale back his HS2 plans for northern England amid soaring costs in 2021.

According to Harper, construction of the Birmingham to Crewe leg of HS2 in central England would now be put back by two years. That part of the line had been due to be extended between 2030 and 2034.

In a written ministerial statement, Harper insisted the government was still "committed" to delivering the high-speed rail link between Birmingham and Crewe.

But he said there had been "significant inflationary pressure and increased project costs" resulting in the delay.

As a result of delayed work on the line going into the capital's centre, passengers will initially have to complete their journey on the Underground network.

London mayor Sadiq Khan condemned the decision to delay the completion of the line into Euston in central London.

"Hundreds of millions of pounds have been spent regenerating the Euston area, and homes and businesses have been demolished to make way for HS2, causing huge disruption for zero reward," he said.

"Local residents simply should not have to spend even more years dealing with the knock-on effects of this giant construction site," he added.

Work on the first phase of HS2 started in 2020 with tunnelling under the Chiltern Hills on the edge of northwest London in 2021.