Internet services in south Asia and the Middle East have been disrupted after Mediterranean undersea cables were damaged by a ship's anchor.
Experts said the chaos caused by the severing of just two undersea cables pointed to the system's vulnerability to terrorist or other attacks.
After the cables were cut by the anchor off Egypt's coast, India woke to discover its network in chaos. Many western companies have web-based operations in India including customer service call centres.
Widespread service failures also hampered a wide swathe of the Middle East. Officials said it could take a week or more to fix the cables, in part because of bad weather. Several countries were struggling to reroute traffic to satellites and to other cables through Asia.
In all, users in India, Pakistan, Egypt, Qatar, Saudi Arabia, the United Arab Emirates, Kuwait and Bahrain were affected.
Israel escaped because its internet traffic is connected to Europe through a different undersea cable, and Lebanon and Iraq were also operating normally.
Such large-scale disruptions are rare but not unknown. East Asia suffered nearly two months of failures and slow service after an earthquake damaged undersea cables near Taiwan in December 2006.
So far, most governments in the region appeared to be operating normally, apparently because they had switched to backup satellite systems. However, the failures caused a slowdown in traffic on Dubai's stock exchange .
The president of the Internet Service Providers' Association of India, Rajesh Chharia, said companies that serve the East Coast of the US and Britain had been badly hit.
"The companies that serve the (US) East coast and the UK are worst affected. The delay is very bad in some cases," he said. "They have to arrange backup plans or they have to accept the poor quality for the time being until the cable is restored".