Ticket resale websites such as Seatwave and Viagogo have been told they must be clear and upfront about their costs as part of a fresh clampdown on the £1bn sector.

The UK’s Competition and Markets Authority (CMA) said it had taken action to ensure that people who bought concert, sports and theatre tickets from the main “secondary market” websites were given better information about charges and any restrictions that might apply.

As a result of the CMA’s intervention, four of the main websites – Seatwave, Viagogo, StubHub and Get Me In – have given undertakings that they will improve the information they provide.

The move comes days after the government carried out a major U-turn and agreed to change the law to clamp down on ticket touting. The measures, announced on 24 February, will give event promoters and venue owners more power to step in and cancel tickets if they see them listed on secondary market websites at inflated prices because they will require sellers to provide details of the seat row and number. At the moment, the sites disclose only the section or block in the venue where seats are located, plus usually – but not always – the row.

The popularity of live music and sporting events, combined with the ease of buying online, has led to an explosion in the number of “bedroom touts” who buy large numbers of tickets with the sole aim of selling them at a profit. Many of these people use the resale websites and there has been growing concern among some politicians and consumer groups that large numbers of genuine fans are losing out because of profiteering.

In-demand events for which tickets are available on the resale sites include the forthcoming production of Hamlet starring Benedict Cumberbatch at the Barbican in London. On 4 March, Seatwave had one seat for sale in row M of the stalls on 14 October priced at £550, plus a booking fee of £100.99 and a £2.99 collection fee, giving a total price of £653.98. Top-price mid-week “premium” seats have a face value of £85.

Some of the measures outlined by the CMA overlap with the changes announced by the government.

The CMA said the improved information provided to buyers would include the face value of the ticket; whether there were any additional charges not included in the price quoted on the site; whether or not multiple seats that were listed together were located together; details of any restrictions that applied, such as a minimum age or if the seat had a restricted view; and a contact email address for buyers to use if something went wrong.

It was also writing to other ticket resale websites and brokers “to explain its expectations about their conduct and their obligations under consumer law”.

Nisha Arora, a senior director at the CMA, said: “We want this rapidly evolving sector to continue to improve across the board so that fans can buy with more confidence.”

Some of the measures announced by the CMA have been adopted by the websites, while others will come into effect over the coming months.

The changes announced by the government in February take the form of an amendment to the consumer rights bill and will be debated in the House of Commons on 9 March. The bill, part of the government’s reform of the UK’s consumer landscape, will make it easier for people to understand and access their rights, including the right to clear and honest information before they buy.

The bill also proposes a set 30-day “no quibble” period for the return of faulty goods for a full refund. Significantly, for the first time, digital content – a large and growing part of the UK economy – will be covered by consumer protection laws.

Jo Swinson, the consumer affairs minister, said UK consumers had spent more than £1bn on downloaded films, music and games since 2012 and, in 2011, more than 16 million people experienced at least one problem with faulty digital content. “This is an important addition to consumer protection and reflects the importance of the sector,” she said.

The bill is expected to become law in autumn.