NEW DELHI — Four undersea communications cables have been severed in the past week, calling into question the stability of the world’s internet and telephone infrastructure.Although experts have said sabotage is not likely the cause of the failures, no one seems to know precisely how the massive cables were cut, who did it, or whether the incidents were related. The cables were relatively new, which precludes the possibility the failures were due to wear-and-tear or age. The Egyptian government also has dismissed another theory — that a ship blown off course during a storm might have been responsible for damage to two Mediterranean cables. No ships were in the restricted-to-maritime-traffic area at the time, Egypt’s Ministry of Communications and Information Technology said.

The Mediterranean outage resulted in an internet blackout for about 70-percent of the Egypt’s users last week. Telephone communication with Europe and the U.S. was disrupted, as well, the ministry said.

Other Middle Eastern countries reported similar problems, especially after another cable about 35 miles off the coast of Dubai was cut on Friday. Even traffic in the U.S. and Europe has experienced slowdowns, network operators noted.

Indian and Egyptian authorities said their countries may have been hit the hardest, because a number of international companies have high-volume customer-service call centers located there. With the four cables down, hold times for already irritated consumers have reached monumental new lengths.

Telecommunications companies have re-routed traffic through other cables, but the bandwidth available is a fraction of what the countries need for normal internet and telephony operations. Consequently, in order to protect the countries’ economies, Egyptian and Indian authorities have asked consumers to forego downloading music and movies until the cables are repaired and operations return to normal. Repairs could take weeks, because the companies that own the cables must send ships to drag them up from the ocean floor in order to replace the damaged segments.

This isn’t the first time communications have been disrupted on a global scale. Smaller incidents have affected Algeria, Taiwan, and India in the past, according to Egypt’s communications ministry, and last year Vietnamese fishermen made headlines when they pulled up Vietnam’s fiber-optic lines in order to “salvage” the copper they contain.

That has some international officials worried that it’s only a matter of time before someone acts maliciously to interfere with world communications.

“…[W]hat if it is sabotage tomorrow?” Colonel R.S. Parihar, the secretary of the Internet Service Providers Association of India, asked in a report published at the International Herald Tribune’s website. “These are owned by private operators, and there are no governments or armies protecting these cables.”

About 95-percent of the world’s telephone and internet traffic travels over undersea cables, according to the International Cable Protection Committee, which works with marine operations to curb damage to the cables. That’s not likely to change soon, as undersea fiber-optics are less expensive and faster than satellite transmission.

Telephone and internet efficiency in the region had reached between 60- and 70-percent efficiency by Monday, officials said.