MERSING - Malaysian authorities on Monday (Aug 12) almost doubled the size of the search area in an operation to look for two Singaporean kayakers in Malaysian waters, four days since they were last seen.

In an update on the rescue operation, the Malaysian Maritime Enforcement Agency (MMEA) said the search area would be expanded to 900 square nautical miles between north of Seri Buat island and north-west of Tioman island in Pahang.

The search operation on Sunday covered 500 square nautical miles in the same area.

A total of four helicopters, one aeroplane, two ships including one from the Royal Malaysian Navy, and five boats were deployed in the operation which began at 7.30am and will end at around 7pm.

At a press conference held at the Penyabong Jetty in Mersing, the MMEA said it has also sent out a broadcast to fishermen and commercial vessels out at sea to look out for the missing kayakers - Mdm Puah Geok Tin, 57, and Mr Tan Eng Soon, 62.

In addition, four multi-purpose vehicles will patrol the coastline between Kuala Rompin and Mersing to search for the two kayakers, who might have drifted to waters in that region based on wind directions.

A total of 104 men were involved in the search and rescue (SAR) operation on Monday.

Johor MMEA director First Admiral (Maritime) Aminuddin Abdul Rashid said that Malaysia has the full ability to conduct SAR within its own waters and hence does not need assistance from neighbouring countries.

Mdm Puah and Mr Tan were in a bright green double kayak when they were separated from their group in the Endau waters in Mersing, Johor, in the evening of National Day's eve, after experiencing strong winds and choppy waters.

A police report was made on National Day and a search and rescue team was sent out around 3.30pm the same day.

Four members of the group of 15 have stayed on to await news of the pair while the rest have returned to Singapore.

The four are close friends of Mdm Puah, who is a businesswoman, and have known her for more than 30 years.

Mdm Puah's husband Peng Mun Kit, 56, said: "My wife was like a sister to them."

The four friends said that they were paddling at the front of the group last Thursday. One of them, who only wanted to be known as Mr Tay, said they only discovered that one kayak was missing after they went ashore on Pulau Mertang Timor, the island which was the intended destination for that leg of the expedition.

"To be honest, given the situation at that time, even if you had blown a whistle, you wouldn't be able to hear it (over the choppy waters)," said one of the four friends, who is also Mdm Puah's godsister and who only wanted to be known as Mdm Ong.

"All of us just followed (the leader). We trusted the organisers," said a visibly emotional Mdm Ong.

The five-day expedition was organised by Mr Goh Khee Wei, who was also the guide for the group. The Straits Times understands that Mr Goh was born in Malaysia and is a Singapore permanent resident.

The other team members pointed out that they did not know Mr Goh personally before joining the expedition but heard that he had organised many similar kayaking trips before. ST understands that Mr Goh manages a group called Kayak Kakis on the Meetup app, which some of the members of the expedition are part of.

ST has also learnt that Mr Goh was one of four people in the group who have kayaked the same route as the one in the current expedition, while the other members have gone on different journeys around Singapore such as the Southern Islands.

Most of them are understood to have had some form of experience in dragon boating or canoeing.

The group had trained on weekends two months prior to the trip by going on weekly sea expeditions around Singapore, such as around Pulau Ubin and around the waters at Sembawang.

According to Mr Tay, the youngest member of the group is 39 years old, while the oldest is believed to be the missing Mr Tan, who's 62. ST understands that Mr Tan is a retired lawyer.

Mr Tay, 56, said he was unaware that they had to get a permit from the Malaysian Maritime Police in order to go on a sea expedition in Malaysian waters.

"We were too naive," said Mr Tay, adding that they had joined the trip at the invitation of their friends without finding out much about what to do.

A spokesman for the MMEA said: "Any activity in the sea, especially those involving groups, you need to get approval from the Malaysian Maritime Enforcement Agency (MMEA) and the Royal Malaysia Police."

Added Mr Tay: "I hope this incident will remind Singaporeans to do things like getting a permit (from MMEA) and informing MFA (Ministry of Foreign Affairs) before going on trips like that."

After the group discovered that Mdm Puah and Mr Tan's kayak was missing at around 6pm last Thursday, Mr Goh called for a speedboat to search for them. They gave up at around 8pm after it got too dark to search for them.

The group rested overnight on the island. At 7am the next day, Mr Goh went out with the boatman on the speedboat to the main island to get help and made a police report.

Mdm Puah's niece Jen Pan, who was one of the family members at Penyabong Jetty waiting for news of the kayakers, said: "My aunt is not your typical auntie."

"She's like a female version of Bear Grylls," added Ms Pan, referring to the British adventurer and survival instructor.

Ms Pan,35, said her aunt is an active lady who is "very fit" and is heavily involved in different sports such as cycling, rock climbing and dragon boating.

"She's super strong, physically and mentally...She can survive this."

* Additional reporting by Trinna Leong