An annual bilateral meeting between Singapore and Malaysia set for tomorrow has been postponed following the intrusion by Johor's Menteri Besar into Singapore waters off Tuas.

Singapore's Ministry of Foreign Affairs (MFA) said yesterday that Datuk Osman Sapian's presence on a Malaysian vessel in Singapore's territory on Wednesday had rendered the 14th Joint Ministerial Committee for Iskandar Malaysia (JMCIM) "untenable".

"Singapore therefore proposed to postpone the JMCIM meeting, and Malaysia agreed," the MFA spokesman said.

The committee was set up in 2007 to study how the two neighbours can work together in the South Johor economic zone of Iskandar.

The Malaysian delegation at this year's meeting was supposed to have been led by Economic Affairs Minister Azmin Ali, Mr Osman and other Johor state leaders.

According to an official source who could not be named due to the sensitivity of the matter, Mr Osman's presence on the vessel was not sanctioned by Malaysia's federal government. "He was told not to do it, yet he went ahead anyway," the source said.

Datuk Seri Azmin told reporters yesterday that the countries mutually agreed to postpone the JMCIM meeting as certain issues on the table were closely related to matters raised in a meeting between their foreign ministers last Tuesday.

"I do not want to interfere with the process by having the JMCIM meeting now. It's a good idea to defer it," he said.

Datuk Seri Azmin will instead have separately scheduled meetings with Singapore's Foreign Minister Vivian Balakrishnan and National Development Minister Lawrence Wong today and tomorrow.

Both countries had agreed last week to establish a working group to study the legal and operational issues relating to the maritime dispute, to provide a basis for further discussions and negotiations.

The dispute over maritime boundaries started after Kuala Lumpur, on Oct 25 last year, unilaterally extended the Johor Baru port limits such that they encroach on Singapore's territorial waters off Tuas.

The new boundary line extends beyond what Malaysia had previously claimed as its own waters in a 1979 map, which Singapore has never accepted. Singapore on Dec 6 extended its own port limits in response, to cover the full extent of the Republic's territorial waters.

Mr Osman on Wednesday night took to social media to share photos of him visiting the MV Pedoman which was anchored off Tuas, saying he received a briefing from Malaysian Marine Department officers regarding the border that is being disputed.

His Facebook post came a day after foreign ministers from both sides met in Singapore and agreed to form a working group to study and discuss the dispute over maritime boundaries.

Mr Osman has since denied that he was in Singapore waters, saying in a Facebook post on Friday that he was visiting personnel on duty to safeguard the boundary, and that the allegations were an attempt at obfuscation.

Relations between Singapore and Malaysia will be a key focus of discussion at the first Parliament sitting of the year tomorrow when Dr Balakrishnan delivers a ministerial statement.

Seven MPs and two Nominated MPs have also filed questions on the ongoing disputes over airspace and maritime boundaries, according to the agenda on the sitting issued by the Clerk of Parliament on Friday.