A 12-member delegation from the Institute of Ocean Technology and Marine Affairs at National Cheng Kung University completed the week-long trip on Sunday, the defence ministry said in a statement.

Taiwan, Vietnam, Brunei, China, Malaysia, and the Philippines claim all or part of the Spratlys, which it is thought may be lying on top of large oil reserves.

"The group was able to use the fact-finding mission to collect first-hand information on issues such as transportation to and from the area, maintaining national security, and protecting the South China Sea's ecosystem," the defence ministry said.

"The visit inspired their patriotism and also renewed our territorial claim."

The move came as local media said Taiwanese authorities were considering extending the runway on Taiping Island, the largest in the disputed waters and some 860 miles (1,376 kilometres) from Taiwan.

Tensions in the South China Sea have risen recently, with China and the Philippines locked in a maritime dispute over the Scarborough Shoal, a reef off the Philippine coast.

Calls for an increase in Taiwan's defence capability in the Spratlys have been on the rise, with rival claimants deploying more troops and adding military facilities in the area.

In May, Taiwanese coastguards said the number of intruding Vietnamese boats last year surged to 106, up from 42 the year before.

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 (two square miles).

Foreign Department spokesman Raul Hernandez said the Philippine coastguard would check on the location of the Chinese vessels in the South China Sea, to ensure they do not enter the country's 200-nautical mile exclusive economic zone (EEZ).

"If these (ships) are going to our EEZ, we will file a protest because this is our EEZ and it is only the Philippines (that has) the sovereign right to explore, exploit and manage the resources in that area," he told reporters.

"We require China to respect the sovereign rights of the Philippines," he stressed.

He cited reports that the fleet of 30 fishing vessels from Hainan had arrived at a point near the Yongshu Reef in the Spratlys, parts of which are claimed by the Philippines, China, Brunei, Malaysia, Taiwan and Vietnam.

China and the Philippines have been in a stand-off over disputed territory within the sea since April, when Chinese government ships prevented the Filipino navy from arresting Chinese fishermen at the Scarborough Shoal.

The Philippines withdrew its ships from the shoal in June in an effort to reduce tensions.

However China had not followed suit, said Hernandez. He said that on Friday a coastguard plane sighted three Chinese government vessels, six fishing boats, two speedboats and several small dinghies still around the Scarborough Shoal.

Chinese-Philippine tensions have increased due to the standoff, with the Philippines accusing China of "duplicity" and "intimidation" at a recent regional forum in Cambodia.

China claims nearly all of the South China Sea, even waters close to the coasts of neighbouring countries. The Philippines says the Scarborough Shoal is well within its 200-nautical-mile exclusive economic zone.