The European Commission has announced a major crackdown on "outrageous" charges for using the internet when travelling in the EU.
Just days after declaring more cuts in mobile phone roaming charges, Brussels stepped up the campaign against network operators by calling for the proposed slashing of "data roaming" costs.
The Commission says consumers are currently charged an average of £2 per megabyte when downloading abroad on another mobile group's network - and in some cases as much as £10.70.
Under plans expected to be approved by MEPs and EU ministers, the maximum operators can charge from July 1 next year will be just 80p per megabyte, falling even further in July 2014 to 45p per megabyte to download data or browse the internet whilst visiting another EU country.
But the Commission acknowledged in a report that its campaign so far of enforced price caps on the cost of using mobile phones abroad - first introduced four years ago - had not had the long-term effect of opening up the market: operators simply apply the compulsory charge at the maximum allowed but have no incentive to cut prices further.
So these proposals also recommend that, from July 1 2014, mobile customers will be able for the first time to opt for a cheaper mobile roaming contract - separate from their national mobile contract - while using the same phone number and SIM card.
And to boost competition further, "alternative" mobile operators - such as supermarkets - will be able to offer roaming services alongside established companies, aided by rules allowing them to use other operators' networks in other member states at regulated wholesale prices.
That, said EU Digital Agenda Commissioner Neelie Kroes, should encourage more operators to compete on the roaming market:
"This proposal tackles the root cause of the problem - the lack of competition on roaming markets - by giving customers more choice and by giving alternative operators easier access to the roaming market.
"It would also bring down prices for data roaming, where operators currently enjoy outrageous profit margins."
The proposals are contained in a new EU Directive on roaming charges to replace existing rules which expire in 2014.
Last week, under the current rules, the Commission cut the maximum permitted mobile roaming call charge rate to 32p per minute - down from 35p - and to 10p for incoming calls.
On July 1 2014, the maximum falls to 21.5p to make a call, and 9p for incoming calls.
But Brussels needs renewed approval to extend its campaign to slash internet roaming costs using smart phones and tablets, and open up competition.
Asked if the new proposals would get through MEPs and ministers, a Commission spokesman said: "It would be hard to imagine them objecting, given the popularity of the cuts we have made under current EU roaming rules."
West Midlands Tory MEP Malcolm Harbour, chairman of the European Parliament's Internal Market and Consumer Protection Committee, welcomed the plans.
He said: "We have been chipping away on this issue of continued overcharging for years. This breakthrough is very welcome news. It provides a long-term solution to the lack of real competition for roaming services.
"Mobile service providers have had it too good for too long and the both the public and businesses have paid the bill."
Fellow Conservative Giles Chichester, MEP for South West England, said: "Mobile providers have seen the travelling public as ripe for a rip-off and now is the time to stop them. This proposal should be adopted quickly to put them on notice: the game is up."
The price comparison website uSwitch.com hailed the new Commission plans as a breakthrough for consumers.
"This has not come a moment too soon," said technology expert Ernest Doku.
"People have been paying extortionate prices for the privilege of using their mobile abroad and millions have been stung by a nasty bill on their return."
He went on: "By lowering call and text charges to a manageable level, consumers now have the freedom to roam at an affordable cost.
"With more than 10 million smartphones now in circulation in the UK, this will be welcome news to gadget lovers."
Allowing mobile users to shop around for roaming deals, regardless of their domestic mobile service, would inject competition into the market - but only within EU countries, he said.
"People should note that this ruling doesn't cover popular holiday destinations in Europe such as Turkey nor many countries further afield," he added.
"Wherever you are going, it's still well worth contacting your network before you travel to ensure that you fully understand the cost of using your phone while you are away.
"Switch off your voicemail and roaming options unless you really need to use them, and remember that international and local SIM cards are a great way to making calls while abroad as you can benefit from far cheaper rates."
Communications company Three UK, the country's largest 3G network, urged the Commission to go further still.
"If the Commission wants to deliver on its objectives to provide a consistent experience for Europe's consumers, it should focus on driving the wholesale rates (for data roaming) down to three cents (2.5p) a megabyte or less," said Three UK Chief Executive David Dyson.
He warned: "Our customers use their smartphones across the UK without fear of cost but must dramatically change the way they use their phones when they go abroad due to high data roaming charges.
"The proposed caps will still leave these charges equivalent to 100 euro (£89) a gigabyte of data by 2014 - a hundred times greater than the current rate enjoyed today by UK consumers."