DENPASAR, Indonesia (AFP) - An Australian passenger who sparked a hijack alert on a flight to Bali has denied being drunk and claimed he banged on the door of the cockpit after mistaking it for the toilet, Indonesian police said on Saturday.

Mr Matt Christopher Lockley also said he was in a state of depression during the Virgin Australia flight on Friday to the resort island, as he was searching for his Indonesian wife with whom he had lost contact.

Security forces rushed to the airport on the Indonesian island when the Boeing 737-800 from Brisbane touched down following a pilot report of a hijacking attempt after a passenger started thumping on the cockpit door. Mr Lockley, wearing flip-flops, white shorts and a T-shirt, was dragged off the plane by heavily armed air force personnel and arrested by police.

The alert prompted a shutdown of the airport and the diversion of several flights.

Indonesian officials initially said Mr Lockley was drunk. But police said on Saturday that the 28-year-old, who is in custody but has been admitted to hospital suffering from fatigue, has denied being under the influence of alcohol.

He told police that before flying, he had taken only two pills of Voltaren, four pills of Panadol - both types of painkiller - and drank two bottles of Coca-Cola, Bali police spokesman Hery Wiyanto told AFP.

"According to him, he was not drunk but suffering from depression due to a family problem," Mr Wiyanto said, adding that police were waiting for alcohol test results, though there was no smell of drink on his breath when he was detained.

Mr Lockley, from the north-east Australian state of Queensland, said that he was on his way to Bali to search for his Indonesian wife, with whom he had lost contact two weeks earlier, according to the spokesman.

Mr Lockley claimed to have been "having hallucinations that somebody followed him and wanted to steal his bag", Mr Wiyanto said. "According to him, he banged the cockpit door as he thought it was the toilet door."

Police earlier quoted a stewardess as saying that Mr Lockley had asked for medicine before thumping on the cockpit door. After this, the crew handcuffed him and put him in a seat at the back of the plane until it arrived in Bali.

Mr Wiyanto said Mr Lockley could be charged for breaking a law against risking passenger safety, punishable by a maximum jail term of two years and a fine of 500 million rupiah (S$55,000).

A spokesman for the Australian embassy in Jakarta said: "We can confirm the arrest of a Queensland man following an incident on board the Virgin airline flight to (Balinese capital) Denpasar.

"The Australian consulate will provide consular assistance as required," it said.