China claims Taiwan as part of its territory and has threatened to use force to bring it under its control.

Taipei fears Beijing could sever communication links to the island as part of an attempt to seize or blockade it.

A Cameroon-flagged vessel was briefly detained by Taiwan's coast guard earlier this month on suspicion of dragging its anchor over an international cable northeast of the island.

But coast guard personnel were unable to board the ship due to rough seas, and the vessel was released because too much time had passed for it to be held longer.

The vessel was owned by a Hong Kong-registered company, with a Chinese address given for its only listed director, the coast guard previously confirmed.

"If there are any suspicious vessel movements in the area where undersea cables are distributed, we will coordinate with the coast guard to monitor them," Defence Minister Wellington Koo told reporters Thursday.

"Once such a situation is discovered, the coast guard will go out first. If the coast guard needs the navy's support, I think we will also go out and coordinate immediately."

China has accused Taiwan's ruling party of having "deliberately hyped" the incident involving the Cameroon-flagged ship.

Koo and several other ministers were questioned by legislators on Thursday over the incident, which has fuelled concerns about the security of the island's telecoms cables.

The world's data and communications are carried across oceans by great bundles of undersea fibre optic cables -- with their high strategic value making them potential targets for attack.

In February 2023, two such telecoms lines serving Taiwan's outlying Matsu archipelago were cut, disrupting communications for weeks.

Taiwan has 14 international underwater cables and 10 domestic ones.

In a report submitted to legislators, the National Security Bureau said suspicious ships carrying flags of convenience sailing within 24 nautical miles (44 kilometres) of Taiwan and close to its undersea cables would be "prioritised" for boarding and inspection.

"In recent years, incidents of undersea cable breakage due to external damage have occurred frequently, highlighting the importance of strengthening the resilience of undersea cables and establishing backup systems," the bureau said, describing it as a "major issue affecting our national security".

In the future, the coast guard would relay reports of damaged undersea cables to prosecutors "immediately after preliminary investigation", the coast guard said in a separate report to lawmakers.