SINGAPORE - Malaysia has cited three documents recently declassified by the United Kingdom to support its application for a revision of an International Court of Justice (ICJ) ruling on Pedra Branca.

They are: internal correspondence of the Singapore colonial authorities in 1958, an incident report filed in 1958 by a British naval officer, and an annotated map of naval operations from the 1960s, the ICJ said in a press release on Friday (Feb 3).

The documents were discovered in the UK National Archives between Aug 4, 2016 and Jan 30, 2017, the release added.

"Malaysia claims that these documents establish the new fact that 'officials at the highest levels in the British colonial and Singaporean administration appreciated that Pedra Branca/Pulau Batu Puteh did not form part of Singapore's sovereign territory' during the relevant period," it said.

"Malaysia argues that 'that the Court would have been bound to reach a different conclusion on the question of sovereignty over Pedra Branca/Pulau Batu Puteh had it been aware of this new evidence'."

Pedra Branca, some 40km east of Singapore and at the eastern entrance of the Singapore Strait, is known as Pulau Batu Puteh by Malaysia.

Britain, and later, Singapore, had maintained control over the island since the 1850s. Malaysia staked its claim to the island in a 1979 map.

The dispute saw both neighbours refer the case to the ICJ, which is based in the Hague, the Netherlands, in 2003.

The Court found on May 23, 2008 that sovereignty over Pedra Branca belongs to Singapore, sovereignty over Middle Rocks belonged to Malaysia, and sovereignty over South Ledge belongs to the State in the territorial waters of which it is located.

A key consideration in its decision was a letter dated Sept 21, 1953, in which Johor's top official informed the British authorities in Singapore that "the Johor government does not claim ownership of Pedra Branca". The Court said in its 2008 ruling it considered this letter and its interpretation of central importance for determining the understanding of both parties about sovereignty over the island, and found Johor's reply showed that as of 1953, it understood that it did not have sovereignty over Pedra Branca.

ICJ's release on Friday (Feb 3) comes as Malaysia's Attorney-General Apandi Ali said in a statement the same day that his country had applied to revise the 2008 judgment a day earlier.

Mr Apandi said the bid was made "upon the discovery of some fact of such a nature as to be a decisive factor, which fact was, when the judgment was given, unknown to the Court and also to Malaysia as the party claiming revision." He did not elaborate.

A spokesman for Singapore's Ministry of Foreign Affairs (MFA) said on Friday that Malaysia had informed Singapore that it had made an application for revision of ICJ's judgment.

"Singapore is studying Malaysia's application and documentation closely and has formed its legal team to respond to Malaysia's application," he said.

The team includes Attorney-General Lucien Wong, Professor S.Jayakumar, Professor Tommy Koh and former Chief Justice Chan Sek Keong.

In its release, the ICJ noted that Malaysia based its application on Article 61 of the ICJ's Statute, which provides that an "application for revision of a judgment may be made only when it is based upon the discovery of some fact of such a nature as to be a decisive factor, which fact was, when the judgment was given, unknown to the Court and also to the party claiming revision, always provided that such ignorance was not due to negligence."

The request for revision must be submitted within six months of the discovery of the new fact, and not later than 10 years from the date of the judgment.

"The proceedings for revision are opened by a judgment which decides whether an application for revision is admissible, that is, whether the above conditions have been fulfilled," ICJ added.

The Court noted that Malaysia, in its application, contends that "there exists a new fact of such a nature as to be a decisive factor within the meaning of Article 61".

Malaysia also asserts that the new fact was not known to Malaysia or to the Court when the judgment was given because it was "only discovered on review of the archival files of the British colonial administration after they were made available to the public by the UK National Archives after the Judgment was rendered in 2008", the ICJ said.

"Malaysia also argues that its ignorance of the new fact was not due to negligence as the documents in question were 'confidential documents which were inaccessible to the public until their release by the UK National Archives'," it added.

Malaysia has asked the ICJ to adjudge and declare its application for revision of the 2008 judgment is admissible.

It has also asked the Court to fix time-limits to proceed with consideration of the merits of the application, ICJ said.