Armoured vehicles and equipment belonging to the Singapore military were seized by Hong Kong customs at a major port in the city after arriving from Taiwan, Singapore's defence ministry said Thursday.

Without mentioning Taiwan, the Ministry of Defence (Mindef) said in a statement that a shipment of Terrex Infantry Carrier Vehicles (ICVs) and other military equipment had been held in Hong Kong since Wednesday due to a "request for routine inspections by the Hong Kong Customs authorities".

"Singapore authorities are providing relevant assistance to Hong Kong Customs and expect the shipment to return to Singapore expeditiously," the statement added.

"The Terrex ICVs were used by the Singapore Armed Forces in routine overseas training and shipped back via commercial means as with previous exercises."

The ministry did not specify the number of vehicles seized or the other equipment involved.

There was no ammunition involved in the shipment, Mindef said in a second statement.

Media reports in Hong Kong and Taiwan said the vehicles were on their way back from a training exercise in Taiwan.

Local TV footage and photographs showed nine apparently impounded vehicles covered with tarpaulin and parked at Kwai Chung terminal surrounded by cargo containers.

Hong Kong customs said 12 containers destined for Singapore from Taiwan carrying "suspected controlled items" had been found and follow-up action would be taken, without providing further details.

A spokesman from Taiwan's defence ministry confirmed the vehicles did not belong to the island and denied involvement with the shipment.

According to Singapore's Straits Times, the vehicles are used by troops during combat proficiency tests conducted in southwest Taiwan.

Singapore and Taiwan have a long-standing defence agreement signed in 1974.

Under "Project Starlight", Singapore troops are allowed to train in Taiwan alongside Taiwanese troops and the city-state has operated three military training camps in Taiwan since 1975, sending up to 15,000 troops a year to train on the island.

But it has in recent years explored closer military ties with China, conducting a joint exercise in 2014.

In June, Singapore and Brunei co-hosted the ADMM-Plus exercises, which involved militaries from all 10 countries in the Association of Southeast Asian Nations and eight other countries, including China, Russia and the US.

Taiwan has recently been chastised by Hong Kong for commenting on the city's political saga which has seen two elected lawmakers, who are advocating independence from Beijing, unable to take up their seats in the legislature after China protested.

Hong Kong is semi-autonomous after being handed back by Britain to China in 1997 and enjoys freedoms unseen on the mainland, but there are increasing fears over Beijing's interference.

Taiwan is a self-ruling democracy, but Beijing still sees it as part of its territory. Relations have grown increasingly tense under the island's new China-sceptic president Tsai Ing-wen who took power in May.