(AFP) A German research student and his guide have disappeared without trace in a Sabah monkey sanctuary, police said today, after searching the small jungle reserve for 11 days.

"We haven't found anything, no sign of either one of them," District police chief Hashim Mohamad Yusuf told AFP .

He said the search for Arne Lennart Cornelius, 21, and local guide Joseph Mohamad Faisal, also 21, was continuing in the 300-hectare Labuk Bay Proboscis Monkey Sanctuary.

Cornelius, from Bremen, was last seen entering the reserve in with Faisal for a one-day field trip on August 30.

His disappearance has been laced with mystery after claims by several villagers that the guide was seen emerging from the jungle the same day.

Speculation has been rife among the villagers that the student has been murdered.

The search teams and German embassy officials have declined to comment.

Report to embassy

German diplomat Gabriele Kowal Manderla, who arrived in Sabah last Wednesday from Kuala Lumpur, said she would be returning to the embassy by the end of the week with a report of the search operations.

"I'm not giving any kind of information (about the search). We don't want to interfere with police investigations," she said.

More than 60 search and rescue personnel with tracker dogs have been combing the swampy conservation park some 30 kilometres from Sandakan in Sabah.

Cornelius's sister Alva flew in to Sabah last Wednesday and was taken straight to the sanctuary. She has since declined to speak to reporters.

Cornelius, who arrived in Malaysia on August 2, had been researching proboscis monkeys in the private sanctuary which was opened to the public three months ago.