Prime Minister Rishi Sunak refused comment on Monday on reports he had decided to delay a key section of Britain's planned HS2 railway - billed as Europe's largest infrastructure project.
An announcement is not expected this week.
A source with knowledge of the project said more details would come in the government's autumn budget statement in November, and the new plan might combine a delay to one section in northern England with an acceleration of a much shorter route between Manchester and its airport.
Below are details about the project.
WHAT IS HS2?
HS2, or High Speed 2, is a planned high-speed railway project that was originally expected to link London with cities in England to its north including Birmingham, Manchester and Leeds.
Since its conception in 2009, the project has faced spiralling costs, cutbacks to its original plans and opposition from various quarters. The first service is currently scheduled to start sometime between 2029 and 2033.
THE RATIONALE FOR HS2
The project is designed to help modernise Britain's rail network, add capacity on busy routes and slash travel times between major hubs.
It will also help bring Britain on par with other European nations that operate lengthy and well-connected high-speed rail networks. Britain only has a small section connecting London with the rail tunnel to mainland Europe.
In terms of speed, HS2's planned top speed of 225 miles per hour (mph) could make it Europe's fastest rail network.
Over the years, successive governments have pitched HS2 as a way to reduce regional economic disparities. It has so far employed nearly 30,000 workers.
Critics say Britain's existing railways, which run on a public-private model, charge exorbitant fares, offer only irregular services and are dogged by delays due to years of underinvestment.
Strikes by thousands of rail workers since last year have only added to the pressure in a country that gave the world the steam locomotive.
HOW MUCH DOES HS2 COST?
Its 2015 budget of 55.7 billion pounds ($68 billion) ballooned to as high as 98 billion pounds by 2019, and in 2020 a review showed that could rise to 106 billion pounds.
The bill has been pushed up by inflation, which ran at around 18% in the construction industry last year, affecting materials like timber, steel and concrete.
CUTBACKS AND CURRENT STATUS
The Y-shaped railway was intended to link London with Birmingham and then Manchester on one leg and Birmingham with Leeds on the other. The government ditched the Leeds connection in 2021 on cost grounds.
It has also delayed the section between Birmingham and the town of Crewe around 60 miles to its north by two years.
Some media reports have suggested that the entire stretch from Birmingham to Manchester could now be scrapped. The source familiar with the project said it could be delayed, while accelerating the route from Manchester to its nearby airport.
The line could also stop at Old Oak Common in northwest London and not central London after the government "deprioritised" the remaining link to Euston station, potentially reducing the appeal and speed of the line.
Work on building the London-Birmingham stretch is currently under way, with machines boring tunnels through the earth, new bridges being built and tons of concrete being produced.
The government has bought hundreds of homes along the proposed route between Birmingham and Manchester and work has begun on a new viaduct in the centre of Birmingham.
WHY IS HS2 SO CONTENTIOUS?
Some groups consider HS2 a vital addition to Britain's rail network but critics have painted it as a vanity project that wastes taxpayers' money. Others have campaigned against it on environmental grounds.
The government's cutbacks to its original plans have also drawn criticism that the project's goal of boosting regional prosperity is not being fulfilled.
WHICH COMPANIES ARE INVOLVED?
A state-funded public body called HS2 Ltd is responsible for implementing the project, with companies such as Kier Group (KIE.L), Balfour Beatty (BALF.L) and Vinci (SGEF.PA) involved in the work.
A joint venture between Japan's Hitachi (6501.T) and France's Alstom (ALSO.PA) will design and build the trains, which are expected to roll off production lines from 2027.
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