Internet service providers in the UK will now be forced to advertise lower and more realistic broadband speeds to potential customers.

Telecom companies currently advertise their fastest speeds when marketing new deals. However, only about 10% of customers actually achieve the top download rates. From May next year, broadband providers can only advertise speeds that at least 50% of customers can get.

Research from the Advertising Standards Authority (ASA) found that the majority of consumers do not understand broadband speeds promised in telecom offers. After the concerns were passed on to the Committees of Advertising Practices (CAP), it decided that the advertising claims needed to be changed.

CAP director Shahriar Coupal said many factors affect consumer broadband speeds: "Our new standards will give consumers a better understanding of the broadband speeds offered by different providers when deciding to switch providers."

Which? expects the changes to come into effect in April, before the May deadline.

The ASA also looked into companies using "fibre Internet" misleadingly. Some Internet providers offer fibre deals where the lines only reach a road-side phone cabinet before making the rest of the trip on the old copper network. No rules were changed on the terminology after ASA decided that most people associated "fibre" as a buzzword meaning 'fast internet'.

Earlier this month, UK telecoms agreed to offer compensation for poor service, including for late setup and outages. That was revealed by Ofcom, the UK's communication regulator, on 10 November.

Recent figures from found that the UK had the eight cheapest Internet bundles in Europe. It also topped Australia, Canada and the United States for affordability. It fell well short of the top 10 (UK was 39th), which included Ukraine and Russia. Iran had the cheapest Internet worldwide at just £5.37 USD for a base package. also ranked the best UK Internet service providers and found Plusnet to have the best value for money, customer service and easiest switching process. Virgin Media had the highest scores for Internet speed and reliability of service.