SINGAPORE - The detention of the nine Singapore Armed Forces (SAF) Terrex infantry carriers in Hong Kong does not comply with international or Hong Kong law, Defence Minister Ng Eng Hen told Parliament on Monday (Jan 9).

And Singapore looks forward to the Terrexes being returned, he said.

Dr Ng explained that the vehicles are the property of the Singapore Government and protected by international law. Under the principle of sovereign immunity, property belonging to a country cannot be seized or forfeited. This principle is well established under international law and also the law of Hong Kong, a Special Administrative Region of China, Dr Ng said.

"Accordingly, the Singapore Government has asserted our sovereign rights over the SAF's Terrexes," Dr Ng said.

Singapore has informed Hong Kong several times over the last two months that the Terrexes belong to the Singapore Government and are therefore immune from any measures of constraint, he said.

Prime Minister Lee Hsien Loong has also written to Hong Kong Chief Executive Leung Chun Ying on the matter, he added.

The Hong Kong authorities have responded that investigations are ongoing and will take some time to be completed, Dr Ng said.

Singapore welcomes this response, he added.

"Adherence to the rule of law has been the fundamental basis for peace and stability for the last half century in Asia. It has enabled countries both large and small to build trust and confidence in one another, cooperate and prosper together," he said.

The nine armoured vehicles were seized by Hong Kong Customs on Nov 23 when they were in transit on their way back from a military exercise in Taiwan.

Representatives of the shipping company APL had held three meetings with Hong Kong authorities but no formal reasons were given for detaining the Terrexes.

Dr Ng said APL's compliance with the rules of the Hong Kong port is a matter between APL and Hong Kong authorities. But that dispute should not affect Singapore's legal position and rights with regard to the Terrexes, he said.

He also reiterated that no military secrets have been compromised as the Terrexes were being used for training and did not contain sensitive equipment.

Following this episode, the SAF has reviewed its shipping procedures comprehensively to "reduce the risk of SAF equipment being taken hostage en route".

It currently does not ship all equipment directly from point-to-point as this will cost three to four times more and add several hundred million dollars to the Defence Ministry's annual budget. Neither does the Singapore Navy have transport ships with the scale and capability to handle all the shipping logistics the SAF needs.

Existing commercial shipping arrangements have allowed the SAF to ship equipment safely and economically without any significant incidents over the last 30 years, he said.

But there are exceptions, such as when advanced weapon and sensor systems are transported, he said. In those special cases, the SAF may charter a whole ship, mandate direct shipping, or deploy protection forces. However, the Terrexes do not fall in this category, he said.

Going forward, the SAF is considering other options, such as housing the equipment overseas to avoid shipping altogether. The Navy's Landing Ship Tanks, currently its largest multi-purpose and transport ships, are also due for replacement. The SAF will study if they should be replaced by ships of larger capacity, he said.