The following clarification was printed in the Guardian's Corrections and clarifications column, Saturday February 2 2008

Dubai is one of the seven emirates that make up the United Arab Emirates; Dubai is also the name of its capital city. It is not a country, as we suggested in the article below.

A flotilla of ships may have been dispatched to reinstate the broken submarine cable that has left the Middle East and India struggling to communicate with the rest of the world, but it took just one vessel to inflict the damage that brought down the internet for millions.

According to reports, the internet blackout, which has left 75 million people with only limited access, was caused by a ship that tried to moor off the coast of Egypt in bad weather on Wednesday. Since then phone and internet traffic has been severely reduced across a huge swath of the region, slashed by as much as 70% in countries including India, Egypt and Dubai.

While tens of millions have been directly affected, the impact of the blackout has spread far wider, with economies across Asia and the Middle East struggling to cope. Governments have also become directly involved, with the Egyptian communications ministry imploring surfers to stay offline so business traffic can take priority. "People who download music and films are going to affect businesses who have more important things to do," said ministry spokesman Mohammed Taymur.

But as backroom staff at businesses across the globe scrambled to reroute their traffic or switch on backup satellite systems, experts said the incident highlighted the fragility of a global communications network we take for granted.

"People just don't realise that all these things go through undersea cables - that this is the main way these economies are all linked," said Alan Mauldin, the research director of TeleGeography. "Even when you're using wireless internet, it's only really wireless back to your base station: the rest is done over real, physical connections."

Despite the clean, hi-tech image of the online world, much of the planet remains totally reliant on real-world connections put in place through massive physical effort. The expensive fibre optic cables are laid at great cost in huge lines around the globe, directing traffic backwards and forwards across continents and streaming millions of conversations simultaneously from one country to another.

One expert suggested that this week's accident should be a "wake-up call" to convince governments that keeping such connections secure should be a higher priority. Officials must spend more time and energy making sure that critical communications such as mobile phones and the net are adequately protected - whether from disaster or a terrorist strike, said Mustafa Alani, head of security and terrorism at the Gulf Research Centre in Dubai.

"This shows how easy it would be to attack," he said. "When it comes to great technology, it's not about building it, it's how to protect it."

Although the direct effect of the Mediterranean accident is being felt as far west as Bangladesh, the greatest impact has been in India, which has the world's fifth largest internet population and an economy that is increasingly reliant on hi-tech communications. The Indian stock markets had already closed when reports of the collapse first surfaced on Wednesday, but the impact of a 50% drop in bandwidth was being felt keenly yesterday - particularly by the country's expansive outsourcing industry.

American corporations were reporting a number of problems with their Indian-based support services and call centres as the domino effect kicked in, although a spokesman for BT - one of Britain's biggest outsourcers - said the company had so far seen little direct evidence of problems. Countries in east Asia and the Pacific remained unaffected as they pipe most of their internet traffic to Europe through the US, but it could be several weeks before things are back to normal in the affected countries.

"It will depend on how bad the damage is, but they'll find the sections in question and bring them up onto a ship for repair before sinking them again," said Mauldin. "It could take a week or possibly two weeks."

The fibre optic wires in question - called Flag Europe-Asia and Sea-Me-We 4 - are some of the most vital information pipelines between Europe and the east. The latter, which runs in an uninterrupted line from western Europe to Singapore, had only recently been opened after a mammoth £500m, three-year installation project. Between them, the two lines are responsible for around 75% of all connectivity in the Middle East and south Asia.

"The problems are really at pinch points where increasingly huge amounts of information are coming through," said Jim Kinsella, chairman of Interoute, Europe's largest fibre optic network provider. He said that improvements are scheduled for submarine cabling, but that plans to send more internet traffic over land connections rather than under the sea had been set back by political wrangling.

"The whole subsea franchise operation is due to change dramatically in the next 18 months, but the question is how we cope in the meantime. You always have to assume that this kind of thing is going to happen."