(Fixes typo in paragraph 6)
SINGAPORE, Jan 9 (Reuters) - Singapore's defence minister said on Monday nine armoured vehicles seized in Hong Kong could not be detained or confiscated and that the city-state had repeatedly asked for their return.
Hong Kong customs seized the troop carriers in November as they were being shipped from Taiwan to Singapore after military exercises on the island that Beijing regards as a breakaway province, sparking tension between Singapore and China.
Beijing, which regained sovereignty over the former British colony of Hong Kong in 1997, then warned countries against maintaining military ties with Taiwan.
Singapore Defence Minister Ng Eng Hen, answering questions in parliament, said the vehicles were Singapore government property.
"They are protected by sovereign immunity even though they were being shipped by commercial carriers. They are immune from any measures of constraint abroad. They cannot legally be detained or confiscated by other countries," Ng said.
Ng added Singapore Prime Minister Lee Hsien Loong had written to Hong Kong chief executive Leung Chun-ying to request their return.
The seizure of the vehicles came amid mounting regional uncertainty and signs of tension between China and Singapore, which has deepened its security relationship with the United States over the last year and remains concerned over Beijing's assertive territorial stance in the South China Sea.
Singapore and Taiwan have a longstanding military relationship that began in the 1970s and involves Taiwan being used as grounds for Singaporean infantry training.
Beijing has grudgingly tolerated this agreement since China and Singapore re-established diplomatic relations in the 1990s.
But China has repeatedly warned Singapore against getting involved in the South China Sea dispute in which China asserts sovereignty over various waters and islands claimed by the Philippines, Taiwan, Vietnam, Malaysia and Brunei.
Singapore has no claims in the South China Sea, but as the biggest port in Southeast Asia, its open economy depends on free navigation in the area.
China has claimed sovereignty over Taiwan since 1949, when Mao Zedong's Communist forces won the Chinese civil war and Chiang Kai-shek's Nationalists fled to the island. Beijing has vowed to bring Taiwan under its rule, by force if necessary. (Reporting by Marius Zaharia; Editing by Nick Macfie)