Confessed British child sex-abuser Richard Huckle, who preyed on poor children in an impoverished Kuala Lumpur neighbourhood, will be sentenced on Monday, judge Peter Rook told the court on Friday.

The sentencing for the serial paedophile had been expected later on Friday but the judge said he wanted to consider mitigating factors put before him by Huckle's lawyers, notably a letter of remorse.

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Judge Peter Rook said his sentencing would begin at England's Old Bailey central criminal court in London at 10:00am (0900 GMT) on Monday.

Huckle, 30, pleaded guilty to 71 counts of child sex offences, including rape. He targeted children while posing as a volunteer working with Christian communities in the Malaysian capital.

His heavily-encrypted computer and a camera contained more than 20,0000 images of child sex abuse, many of which showed him committing offences including rape.

During Friday's hearings, Huckle's lawyer Philip Sapsford asked for leniency in the sentencing as his client had, in pleading guilty, spared a jury from being exposed to the images of his abuse.

The material, recovered from his laptop, had been placed on the "dark web", a difficult-to-access part of the Internet.

In the letter of remorse, written on May 23 this year and read to the court by Sapsford, Huckle acknowledged "the scale of the damage I have caused".

"I completely misjudged the affections I received from these children.

"My low self-esteem and lack of confidence with women was no excuse to be using these children as an outlet."

He said he was "gullible to be easily influenced" by the "pathetic, perverted lust of those who drew me into the dark net".

Huckle said he hoped help would be made available to the victims of the "disgusting behaviour I performed on them".

"I am open and eager to rehabilitate from this offending behaviour," he wrote.

"In no way do I want to be treated as a martyr to child sex tourism in Malaysia.

"This was all my own doing as a consequence of my own immaturities.

"I am deeply remorseful and regretful of what has happened and will do all I can in being proactive towards rehabilitating myself."

Huckle, who is in custody, was flanked by three officials in the dock and was led away to await his sentencing.