Iain Coucher is Network Rail's chief executive. The allegations have been made in a series of articles in satirical magazine Private Eye, and include details of how Mr Coucher allegedly had the use of a Coutts World Card which allowed him to draw up to £100,000 a day in business expenses.

Other claims include that he was paid £20,000 a year for renting an elegant apartment in a Georgian square in central London and that he was paid £13,000 a year towards the cost of running his Aston Martin.

Network Rail said "several members" had raised the allegations with Mr Haythornthwaite to find out what he was going to do about it.

In an email to the 100 public members at Network Rail, Mr Haythornthwaite wrote: "Whilst Private Eye does not always have a reputation as a document of record, the innuendo and occasional specific allegations that have been appearing over the past 18 months in it and various other publications are harmful to the reputation of the company and the individuals concerned."

He added: "I will be reviewing again the findings of those investigations and looking at the only new allegations to emerge in this article."

A Network Rail spokesman dismissed the claims as "nonsense". He added: "Naturally, [the chairman] wants to allay [members'] concerns by reporting back to them."

Mr Coucher, who resigned in June after three years in the role, will receive £641,349 in bonuses on top of his salary of about £600,000.