The first undersea telecommunications cables linking Taiwanese and mainland Chinese territory have been completed, a company official said Thursday, amid fast warming ties between Taipei and Beijing.

The two fibre optic cables link the city of Xiamen in southern China with the Taiwanese-controlled Kinmen island group, which lies just off the coast of China and around 200 kilometres (125 miles) from the main island of Taiwan.

The cables are due to go into operation on Tuesday, an official with Taiwan telecom operator Chunghwa Telecom told AFP.

The official, who asked not to be named, said the company had invested around Tw$100 million ($3 million) in the joint venture involving three other Chinese telecom operators.

The cables are yet another sign of fast improving ties between Taiwan and China. The two split in 1949 at the end of a civil war and the Kinmen island group was often a flashpoint during the Cold War period.

The Chinese army fired more than 470,000 shells on Kinmen and several other islets in a 44-day bombardment in 1958, killing a total of 618 servicemen and civilians and wounding more than 2,600.

China was still bombarding the island as late as the 1970s, although by then the shells were stuffed with propaganda leaflets.

Ties have warmed since Taiwan's China-friendly Ma Ying-jeou administration came to power in 2008 on a platform of beefing up trade and tourism links. He was re-elected in January for a second and final four-year term.

Kinmen has become a popular attraction for tourists from both sides.