Subsea cables are often damaged by ship's anchors and seismic activity
Internet and phone communications between Europe, the Middle East, and Asia have been seriously disrupted after submarine cables were severed.
It is thought the FLAG FEA, SMW4, and SMW3 lines, near the Alexandria cable station in Egypt, have all been cut.
A fault was also reported on the GO submarine cable 130km off Sicily.
Experts warned that it may be days before the fault is fixed and said the knock on effect could have serious repercussions on regional economies.
Jonathan Wright - director of wholesale products at Interoute which manages part of the optical fibre network - told the BBC that the effects of the break would be felt for many days.
"This will grind economies to a halt for a short space of time," he said "If you look at, say, local financial markets who trade with European and US markets, the speed at which they get live data will be compromised."
"If you think how quickly trades can be placed, if they are suffering from bad latency times, then by the time a trade is placed, the market may well have moved on."
The cause of the break is as yet unknown, although some seismic activity was reported near Malta shortly before the cut was detected.
A second subsea cable to Malta is currently being laid
In a statement released in relation to one of the breaks, France Telecom said: "The causes of the cut, which is located in the Mediterranean between Sicily and Tunisia, on sections linking Sicily to Egypt, remain unclear."
The French firm said it was sending a ship out to fix the line between Italy and Egypt, although it could take until 31 December to fully repair the line.
The main damage is to the four submarine cables running across the Mediterranean and through the Suez Canal.
It is thought that 65% of traffic to India was down, while services to Singapore, Malaysia, Saudi Arabia, Egypt, Taiwan and Pakistan have also been severely affected.
Earlier this year, the same line was damaged in the same area - off the Egyptian coast - although only two lines were snapped then.
"We've lost three out of four lines. If the fourth cable breaks, we're looking at a total blackout in the Middle East," said Mr Wright.
"These three circuits account for 90% of the traffic and we're going to see more international phone calls dropping and a huge degradation in the quality of local internet," he added.
"Normally you would expect to see one major break per cable per year. With four you should have an insurance policy. For this to happen twice in one year, on the same cable, is a serious cause for concern."
A selection of your comments on this story:
Over weekend 13th to 16th December had considerable delays and time-outs reaching my email server in Germany and various homepages in Switzerland and the UK. I suspected that a breakdown somewhere was at fault but was surprised to be unable to get any info from Google etc. You can check your ADSL speed easily but finding the speed of a connection from one continent to another seems to be lacking.
John Russell, Toowoomba, Queensland, Australia
I began downloading something this afternoon but late this evening it suddenly became six or seven times slower. I now know why.
Max, Wallasey, UK
I teach English at a high school in Sisaket. The last few days our connections have been very, very slow. Yesterday, when I was trying to teach some students how to use Limewire to download movies and songs, the connection seemed to be nearly non-existent. We thought that maybe the wire to our building had been damaged.
Les Blane, Sisaket, Thailand
I work at a call centre. We are unable to make calls as the latency is too high which only ends up in dropping of every call that we dial and the internet speed has been downgraded like anything. I hope this gets fixed by Sunday (December 21), otherwise we will be in total blackout and will suffer in great loss of business in this high time.
Adeel Awan, Karachi, Pakistan
Yesterday's cuts in Malta were a big hassle to all GO subscribers. One here seems to all of a sudden realise how dependent we all are on internet. At least alternative measures have been taken in Malta by GO in conjunction with another internet service provider which was not affected, and therefore today almost all Malta is back to normal - albeit with slower connections.
George Bugeja, Zebbug, Malta
Internet is very slow. I could not connect to any sites except by using a socks server I installed on one of my servers located in USA. I wonder why they do not use separated cables with separated routes? Why are the four main cables located with each other? It is just like putting all eggs in the same basket.
Walaa Waguih, Alexandria, Egypt
Currently staying in Brazil - cannot access virginmedia.com - don´t know if this has anything to do with the above.
Roger Francomb, Sao Paulo
One of my favourite sites was unavailable earlier. It's back up, but from conversations there are still others who cannot access the site, some in the same country as the site's servers.
Michael Harvey, Framingham, Massachusetts, United States
I had trouble with the net from earlier today which I thought had something to do with the local SP. The link gets disconnected frequently and even when you are connected it is terribly slow.
Josekutty, Doha, Qatar