The dad of British backpacker Amelia Bambridge fears that she has been abducted.
The 21-year-old was last seen at a beach party on the Cambodian island of Koh Rong on Thursday morning.
As her family members fly out to join a local search party and well wishers donate money for the rescue effort back at home in Worthing, West Sussex, fears for her safety are growing.
When asked by a reporter dad Phil Bambridge said he suspected she had been abducted.
"I don't think she's had an accident," he said.
"If she'd just had an accident, she'd have been found by now."
As the effort to find her continues around 150 people have been split into two groups, with one searching the ocean and the other the jungle.
Major General Chuon Narin, police chief of coastal Preah Sihanouk province, said: "As of now, the searchers have no news about her whereabouts and they have expanded the area they are searching to make sure all possible sites are checked.
"I can't say whether Bambridge was killed or got lost in the island's jungle."
Amelia set off on her trip on September 27, when she flew to Vietnam, her family said.
They were alerted to her disappearance after she failed to check out of the Nest Beach Club hostel.
Her passport remained at the hostel.
Staff at Police Beach, a private venue that stages regular events, found Ms Bambridge's purple rucksack, containing her purse, phone and bank cards, the morning after she went missing.
Georgie Bambridge spoke to her sister on the phone in the hours before she was last seen.
"She went to the Police Beach party on Wednesday night - the last time I spoke to her was Wednesday daytime," she told Sky News .
"She said it was doing so much for her confidence and she found so many people who were friendly.
"She said 'Everyone is so cool here' and couldn't be happier."
She went on to say that her "role model" sister "would never drink to excess" and was "always in control", adding: "She would always be looking out for me, it's not like her to not look after herself.
"I just don't know what's happened."
