The company built the HS2 railway line between London and Birmingham and said it was investigating "accusations" about some of the "labor suppliers" practices of the project.

HS2 Ltd is working on two companies to provide workers with the West Midlands area to build high-speed lines.

It is understood that it is related to the bills of the employees provided.

The Ministry of Transport said it will ensure that "any misconduct in the HS2 supply chain" is handled "fully".

The existence of the HS2 investigation, which began first reported on Monday earlier this year.

According to this article, the matter involves misclassification of employees and requires them to charge them for inflated rates.

It is understood that the two companies in the process of focusing are providing workers with one of the HS2 contractors, Balfour Beatty Vinci.

A HS2 spokesman said it dealt with “all whistleblowers’ allegations” and added that Balfour Beatty Vinci “implemented other surveillance and controls.”

It is understood that a labor supplier is still suspended and inquiry continues.

A spokesman for the Ministry of Transport said the government and HS2 “put great importance on all whistleblowers’ allegations and had zero competitive attitudes towards fraud, bribery and corruption.”

“So we will ensure that any requests are made for misconduct in the HS2 supply chain.”

Police and HMRC are not considered involved.

Work is currently underway to establish nearly 140 miles of high-speed route between London and the West Midlands.

The HS2 project was announced in 2009 to increase the capacity of North-South Railway Connection in England, aiming to reduce travel time, create jobs and promote the UK economy.

The initial plan was to establish the route in two phases - the first to connect London and Birmingham and the second to Manchester and Leeds.

However, since the announcement of the project, the project has suffered various setbacks and spiral costs, and finally the Conservative government decided to abolish the second phase. The Labor government said it would not be restored.

According to HS2 Ltd., most of the work in London - Birmingham has been completed - more than 75% of the tunnels are completed.

Additionally, the mayors of Greater Manchester and West Midlands have revealed plans to connect it to their area’s new rail routes that will rely on private investment and cost less than the north of the abandoned HS2.

Official estimates that HS2 costs will change several times over the years.

Last October, the government announced that the minister would play a direct role in overseeing the construction of the line in an attempt to “grasp” the rising costs.

The government has previously said it has soared due to “poor project management, inflation and poor performance in supply chains”).

It is estimated that in 2012, the price of HS2 Phase 1 (London to Birmingham) is £20.5 billion (at 2019 prices). The government's latest estimate of the overall cost is £45 billion to £54 billion in 2019 - but HS2 management estimates that figure is more like £49 billion to £57 billion.

According to a House of Commons research briefing, the cost increase is "driven by high inflation and range changes, poor ground conditions, and biased than expected and optimistic bias".