The tax affairs of the secondary ticketing industry are being targeted by HM Revenue and Customs, the Victoria Derbyshire programme has learned.
It comes after some sites were criticised during a Department of Culture Media and Sport select committee hearing earlier this month.
An industry expert suggested the volume of ticket sales was not reflected in company accounts.
Culture Secretary Karen Bradley said she would raise the concerns with HMRC.
At the hearing in November, ticketing expert Reg Walker said: “This is meant to be a £1.2bn industry in the UK alone, and yet we can only find a turnover of around £200m on published accounts.”
In response, Mrs Bradley said she would “ensure that the concerns highlighted during the evidence session with regards to the under-reporting of income are raised with HMRC”.
She met members of the live entertainment industry on Wednesday to discuss issues raised during the select committee hearing.
In a statement, HMRC said: “HMRC will always act where we believe individuals and businesses are not declaring their income correctly or paying the tax that they owe.
“Our compliance teams target specific sectors and locations where there is evidence of high risk of tax evasion and fraud and we use intelligence from various sources.
“In all cases, we look at compliance against a variety of taxes including VAT, self-assessment and corporation tax.”
The four biggest secondary ticketing websites – Seatwave and GetMeIn, which are both owned by Ticketmaster, plus Viagogo and Ebay-owned Stubhub – are already under investigation by the Competitions and Markets Authority.
Ticketmaster and Stubhub have declined to comment on the HMRC statement, while Viagogo are yet to respond.
Selby and Ainsty MP Nigel Adams has proposed an amendment to the Digital Economy Bill to outlaw the use of computer programmes known as bots, which touts use to buy up large numbers of tickets to resell them at higher prices on secondary platforms.
He joined other MPs and members of the live entertainment industry outside Parliament on Monday to call on the government to accept the amendment.
Watch the Victoria Derbyshire programme on weekdays between 09:00 and 11:00 on BBC Two and the BBC News Channel.