The defence ministry in November completed building a runway on Taiping island, the biggest in the Spratlys, he said.

'The air force commander-in-chief flew there last week to test the runway,' he told reporters, referring to a clandestine test flight by a Taiwanese C-130 transport plane.

Vietnam has already protested over the flight, which came to light this week.

Mr Lee confirmed reports that Mr Chen planned to travel to the islands, which are claimed by Taiwan, Vietnam, Brunei, China, Malaysia and the Philippines.

'If the president decides to go there, I will go with him,' he said. 'There is nothing wrong to do so, because it belongs to the Republic of China (Taiwan's official title). The Republic of China began deploying troops on the Taiping island back in 1956,' he said.

But 'the other countries in the region did not make claims until reports of rich natural resources reserves surfaced', Mr Lee added.

He urged joint efforts by the rivals to explore the potentially oil-rich Spratlys while shelving territorial disputes.

All claimants except Brunei have troops based on the archipelago of more than 100 islets, reefs and atolls, which have a total land mass of less than five square kilometres. -- AFP