Tremors from Tuesday's earthquake near the southern tip of Taiwan damaged undersea cables, disrupting internet and telephone communications across Southeast Asia.

Telecommunications companies said the 6.7-magnitude earthquake forced them to activate backup systems after tens of millions of internet and telephone users were cut off from service Wednesday.

Crews in Pingtung County, about 350 kilometres southwest of Taipei, clear rubble from a collapsed building after the earthquake struck Wednesday.
(David Lee/Asssociated Press)

The earthquake claimed the lives of two Taiwanese residents and injured more than 40 people, and the communications breakdown also hit the island hard, as Taiwan is Asia's fifth-largest economy.

Initial tremors on Tuesday set off alerts about a possible tsunami on the second anniversary of the waves that killed about 230,000 people in Southeast Asia, but the region was spared further disaster.

Chunghwa Telecom Co., Taiwan's largest phone company, said the tremors damaged two underwater cables off the Taiwanese coast, which link communications between several Asian countries.

As a result, the company lost at least half of its telephone capacity, meaning connections have been cut off to China, Japan and other parts of Southeast Asia, company spokesman Wu Chih-ming said.

Repairs could take weeks

The island's undersea cable system includes seven interconnected lines, in which damage to one line can affect the others.

Wu said it could take weeks of repairs until calls can be properly routed and connected, and damaged portions must first be hauled on board ships for the work to begin.

"On average, if the problems with the cables are less than 1,000 metres deep, the repair teams should only need two weeks," he said. "But if it's deeper, it could take three weeks."

Neighbouring countries, including China, Japan and South Korea, have also reported online and telephone glitches.

In Hong Kong, web users could not connect to sites in parts of the U.S., Taiwan and South Korea.

Repair vessels are not expected to begin work before the end of next week.

With files from the Associated Press