The newly privatised business has caught the interest of investors, some of whom wanted to profit from short-term selling of the shares, or stagging, in the first days of its listing.

The government sold shares in Royal Mail for 330p, leading to criticism it undervalued the business in a share issue which was seven times oversubscribed, according to some reports. The stock climbed to as much as 475p in grey market trading on Monday.

A panel of MPs intends to question the bankers who advised the government on the pricing of the IPO, according to a report by Sky News.

Meanwhile, a group of City traders is considering making an official complaint to business secretary Vince Cable after many were excluded from the Royal Mail float last week.

The huge demand led the government to reject any application made for more than £10,000 worth of shares, with 500 institutional investors who applied getting no shares at all.