SINGAPORE - A joint exercise was conducted by the Republic of Singapore Navy (RSN) and the Singapore Police Force (SPF) on the island of Pedra Branca in August, said the RSN on its Facebook page.

As part of it, a scenario involving an armed civilian intruder was simulated, with the RSN and police intercepting and taking down the threat, the navy said on Friday (Sept 29).

"The RSN and the SPF conduct regular exercises to ensure that our contingency plans for the defence of Pedra Branca against any threats or intrusions are well practised," the Facebook post read.

The exercise was held following "months of planning and preparation", the navy said, adding that a round-the-clock watch over the island is maintained to guard against intrusions.

The waters off Pedra Branca were the site of a fatal collision between an oil tanker and a United States warship on Aug 21.

The island was the source of a territorial dispute between Singapore and Malaysia. The International Court of Justice (ICJ) had, in a 2008 judgment, awarded the sovereignty over Pedra Branca to Singapore and neighbouring Middle Rocks to Malaysia.

But in June, Malaysia filed an application at the ICJ to declare that the waters around Pedra Branca are within its territorial waters.

Singapore has said that it will oppose the bid, which it called unnecessary and without merit.

In August, a Malaysian navy ship, KD Perdana, berthed for the first time at the new Abu Bakar maritime base in Middle Rocks.

Malaysia's navy chief, Admiral Ahmad Kamarulzaman Ahmad Badaruddin, said in August that while the vessel was not being permanently positioned there, it would still frequent the base and carry out patrols in the area with other vessels, to ensure maritime security.