Rajesh Chharia, the president of the Internet Service Providers' Association of India, 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," Chharia was quoted by the Associated Press as saying.
"They have to arrange backup plans or they have to accept the poor quality for the time being until the fiber is restored."
Internet traffic rerouted
Praveen Mathur, an executive at Streit India Advisory Services, an equity investment consulting firm based in New Delhi with clients in the US and Canada, said the company's business would "definitely be affected" if the outage took a long time to fix.
"The internet service has been close to nonexistent"
Steit India executive
"The internet service has been close to nonexistent. Most of our ... consultation with our overseas customers is done online. The internet is our main business tool," he said.
TeleGeography, a US research group that tracks submarine cables around the world, said the Mediterranean undersea cable cuts reduced the amount of available capacity on the route from the Middle East to Europe by 75 per cent.
The group warned that until service was restored, many providers in Egypt and the Middle East would have to reroute their traffic around the globe, to Southeast Asia and across the Pacific and Atlantic oceans.
Officials said it could take a week or more to fix the cables and several countries affected by the outage moved to reroute traffic to satellites and to other cables through Asia.
Such large-scale disruptions are rare but have occurred before. East Asia suffered nearly two months of outages and slow service after an earthquake damaged undersea cables near Taiwan in December 2006.