Pictured: Incest father on 'boys holiday' to Thailand as his captives languish in his secret dungeon thousands of miles away

These holiday snaps of Josef Fritzl were made public yesterday, as more bizarre details of his crimes emerged.

According to police, Fritzl claims he locked up his daughter Elisabeth for 24 years to save her from drugs.

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Holiday monster: Evil Fritzl takes a snap during a sunshine holidays with friends

Smiling jailor: Josep Fritzl grins during a boat-trip on a holiday to Thailand

During this time, he admits that he submitted her to terrible abuse and she bore him seven children - one of whom died.

At the time some of these pictures were taken, in the late 1990s, she was in the cellar with two of their offspring.

Relaxed: Incest father Fritzl on holiday

He told detectives: "I locked up Elisabeth. But only in order to protect her against drugs. She was a difficult child."

There is no suggestion that his daughter - 18 at the time of her imprisonment - was involved with drugs.

In fact, the retired electrical engineer drugged her himself in order to get her to the basement prison.

When questioned about the sexual abuse, which began when she was only 11, he admitted he fathered her children and delivered them in the grim surroundings. But he was nonchalant about his behaviour.

He said: "Yes I did have sex with her, but I haven't for many months now."

Fritzl also explained why he took three of Elisabeth's children from her to lead a relatively normal life "upstairs" with him and his wife.

It was because the youngsters were "cry babies" and he was afraid the noise they made would expose his double life, police said.

In fact no one heard any cries for help from the sound-proof cell.

Detective Franz Polzer, who is leading the investigation, said: "Even though they shouted, they were not in a position to let anyone hear them."

The detective told a press conference yesterday that Fritzl went to elaborate lengths to maintain his subterfuge. Last week he forced Elisabeth to write a letter explaining she had decided to return home after supposedly running away to join a cult in 1984.

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The bedroom: Narrow corridors divide the family living quarters beneath the grey concrete villa

Captive: This tiny door led to the underground labyrinth where the four were held

He posted it from a location hundreds of miles away.

"You can be sure that this man left nothing undone in order to deceive the family, his wife, the relatives, the children and everybody around him," added Polzer.

"He had no scruples to use every possible means to deceive the public and cover up his crime. He was a very cunning man."

A police source said: "He is showing no sign of regret whatsoever.

"He is so arrogant that I don't actually think that he thinks he has done anything wrong."

Fritzl's lawyer Rudolf Mayer was asked if he showed any remorse. In what appears to be an indication that he did not, Mayer replied only: "I cannot say at this point."

Certainly, Fritzl was happy enough in the late 1990s to take the sunshine break to Thailand with a male friend.

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He is thought to have stockpiled food and left the captives to fend for themselves.

Other holiday snaps released yesterday show him on a trip to the Mediterranean in the late 1970s.

It is not known whether this was around the time that he began abusing Elisabeth.

Last night Fritzl, who police believe acted alone without an accomplice, was being held at a police station.

Doctors said he was not showing suicidal tendencies but he is under 24-hour supervision.

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Sinister: The doorbell into the home Fritzl shared with wife Rosemarie and his three adopted children

The eminent Austrian psychiatrist Reinhard Haller said: "Fritzl appears to have been driven by pronounced narcissism and a need to exercise power over others - and that may help explain how he got away with the abuse for so long.

"This man must have been insane and must have felt he was far superior to others."