Johor's Menteri Besar Osman Sapian took to social media late on Wednesday night to share photos of him visiting a Malaysian government vessel anchored in Singapore's territorial waters off Tuas.
His Facebook post came a day after foreign ministers from both countries met in Singapore and agreed to form a working group to study and discuss the dispute over maritime boundaries.
Mr Osman said he visited officers on duty aboard Malaysian Marine Department (MMD) vessel MV Pedoman. Johor state exco member Tan Hong Pin was also seen in a photo.
"Captain Mohamad Azlan Aziz explained the maritime boundary limits in dispute between two countries," Mr Osman wrote. "I thank, for their service and sacrifice, members of safety agencies and public officers who are committed to monitor and defend our waters."
Also seen in Singapore waters were Malaysian Maritime Enforcement Agency vessel KM Marudu and MMD vessel Tanjung Puteri, which Mr Osman used to visit MV Pedoman in Singapore waters.
Responding to media queries yesterday, the Maritime and Port Authority of Singapore (MPA) said there were five Malaysian government vessels in Singapore's waters as of 6pm on Wednesday.
The MPA also confirmed that two vessels remained in Singapore waters as of 6pm yesterday.
On Tuesday, Foreign Minister Vivian Balakrishnan and his Malaysian counterpart Saifuddin Abdullah had announced that the working group will be headed by permanent secretary for foreign affairs Chee Wee Kiong and his Malaysian counterpart Muhammad Shahrul Ikram Yaakob. It will study and discuss the legal and operational matters, to de-escalate the situation on the ground and provide a basis for further discussions and negotiations.
The working group being formed to discuss issues surrounding the two port limits is to report to the foreign ministers in two months. Both ministers had also stressed the need to keep the situation on the ground calm to allow talks to take place.
Kuala Lumpur had on Oct 25 last year unilaterally extended the port limits for Johor Baru port, such that they encroach on Singapore's territorial waters off Tuas. As a result, Malaysian government vessels had intruded into Singapore waters.
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.
After the Tuesday meeting, the foreign ministers also announced that Malaysia will immediately suspend its permanent restricted area over Pasir Gudang for flights, while Singapore will do the same for new aircraft landing procedures for Seletar Airport. The arrangement will be for a month, in the first instance.