KUANTAN - Before British national Gareth David Huntley was going to start work in the Singapore office of multinational insurance group RSA, he made a trip to Malaysia's scenic Tioman Island off the state of Pahang to take part in a sea turtle conservation project.

On Tuesday, he went on a solo waterfall trek. The 34-year-old portfolio analyst told his girlfriend in a text message that the trek was "not a piece of cake" before setting off, and no one had heard from him since.

His concerned family members and friends had called on the Malaysian authorities to step up search efforts. "It's become very unclear whether the Malaysian authorities understand the urgency of the situation and whether they're acting fast enough..." wrote the administrator of a Facebook group "Find Gareth Huntley".

Malaysian police on Saturday said they were trying their best to track down Mr Huntley. Rompin police chief Johari Jahaya said his team also engaged locals who were familiar with the area around Lubuk Teja waterfalls to help with the search. "But if we cannot find (him) after several days of searching, what more can we do?" he was quoted as saying by The Star Online.

Mr Huntley's brother Mark told the BBC he was not convinced that a full search had been launched. "It seems... it's only been the locals and the people who know my brother who have been searching."

He added that he hoped British authorities could "put more pressure on the Malaysian police force and search and rescue to do more to intensify the search". His parents would be flying to Malaysia to follow up on the case.

"At this stage I feel it is essential that the search be intensified as time is running out for Gareth, so I would really appreciate the support of the Malaysian authorities and the UK government with this," Mr Huntley's mother Janet Southwell was quoted as saying in the report.

Mr Huntley was until Nov 2013 a portfolio analyst with RSA's London office, according to his Linkedin profile. He had been travelling in South-east Asia before landing a job in the Singapore office, according to the Facebook group's administrator.