Family and friends of a British man missing in the Malaysian jungle have criticised the "laughable" attempts to find the 34-year-old, as they tighten pressure on Prime Minister David Cameron to help.
Gareth Huntley has not been seen since he went on a trek to a waterfall in Tioman Island, off the south eastern coast of the country's mainland, on Tuesday morning.
Reports that a team of up to 30 people have been searching are false, according to Mr Huntley's close friend, Kyle Neo Kai Fu, who is on Tioman Island.
He said that, despite reports to the contrary, Malaysian officials' response has been tepid, with just a handful of police officers working on the case - with nobody in overall charge of the operation.
Mr Fu said: "I am shocked that in spite of the fantastic public response and in spite of all the assurances offered there is a sickening lack of action.
"David Cameron and William Hague have to step up back in London and ensure the local people here get the vital resources they need from Malaysia's police force to help us find Gareth."
Mr Fu said investigators have no GPS navigation equipment or maps to help scour the dense wilderness, while the officer leading the small operation has left.
He added: "The idea that there is a proper professional search going on is laughable."
Mr Huntley's mother, Janet Southwell, said "real help" was needed to find her son, from Hackney in east London.
In a direct plea to Mr Cameron, she said: "As a father, you know that we'd do anything for our children and so I'm humbly asking that you make one phone call to help my missing son, Gareth.
"Please do the right thing Prime Minister and make one phone call to the Malaysian leader to insist that they deploy real help to find Gareth before time runs out. He is out there in the jungle and he needs help.
"We've been hugely heartened by the public's fantastic support so far but we urgently need firm action from the Government - not standard press assurances of 'working with authorities'. We need boots on the ground, search teams and dogs so that we can bring our son back alive.
"As our Prime Minister I write to you but as a mother too, I hope you'll help me."
She told Sky News that the police response had been "incredibly slow".
She said: "The locals were, apparently, brilliant. They were out, very quickly, looking, searching as best they could, through terrain which they obviously know very well, but from what we understand the police response was incredibly slow."
She said it was out of character for him to go missing. "He's got an exploring nature, he's intelligent, and hopefully his ability to apply himself will get him through this.
"He was on a break from work, he was due to start a new job in Singapore next week. It's totally out of character for him to go missing, he just would not do it. He knows there are too many people who care and love him."
The missing man's brother, Mark Huntley, a 30-year-old web developer from Leeds, said today: "The media response has been hugely appreciated but we need real action now to find Gareth.
"Gareth's been missing now for five days and he's alone in the jungle. This was a man working out there as a wildlife volunteer - he deserves our assistance."
Mr Huntley had been working at the Juara Turtle Project. Fellow volunteer Charles Fisher said a group went to search for him after he did not return from the "huge wilderness".
They checked various different routes to the waterfall 6km away that he might have taken, while a further search the next day also proved fruitless.
Mr Fisher added: "Then the afternoon of the second day the police were informed - they sent a couple of members of the police force along to have a look but didn't go far or look very much - they were just sort of assessing the situation.
"Then the next day, the 29th, a group of volunteers went out and looked then came back again. Another group from the local community also went out as well and went deep into the jungle. The police were no longer physically looking at that point - I think they were arranging for a search party but nothing happened that day.
"Then today we've just been hoping the state police will do a proper search but nothing has happened yet. I don't know what's going on.
"It's a huge wilderness out there - a remote location. He could have taken a wrong turn and just got lost in another valley - we just don't know. The trouble is the police probably don't have proper search equipment - they need extra support."
A Facebook group has been set up to raise awareness about Mr Huntley's disappearance.
A Government spokesman said: "The Government is working hard with the Malaysian authorities to ensure a comprehensive search is carried out to find Gareth Huntley.
"The Malaysian police have already deployed a search team using dogs and boats, and the Foreign Office continue to work with the Malaysian authorities. An FCO consular team is en-route to Tioman Island to meet the family when they arrive."