A suspected illegal immigrant from Sierra Leone was locked up indefinitely on Monday for raping a 13-year-old girl and sexually assaulting another.

Lesley John Eku Baker, 33, was ruled mentally unfit to stand trial at Isleworth Crown Court but was detained under the Mental Health Act indefinitely.

He told the young teenagers he was 15 when he met them in Lampton Park, Hounslow, and invited them to his home on December 17 last year.

The two girls and a 16-year-old boy, who cannot be named for legal reasons, went with Baker to a "sparsely furnished house" in Harte Road that afternoon, prosecutor Jonathan Ingram told an earlier hearing.

Within minutes of arriving Baker had put his arms round one of the girls and tried to kiss her.

She pushed him off while the boy went and got a knife from the kitchen.

"Baker was grabbing at the girl's jeans and pulling the buttons on them," counsel said.

They all went up to his bedroom where Baker pushed the girl on to the bed and tried to kiss her. When the other two left the room Baker locked the door.

Mr Ingram said: "She screamed for help as he tried to force himself on her again."

The boy kicked open the door, grabbed his friend and they ran downstairs not realising that the other girl was alone with Baker. They rushed back and caught Baker raping the other girl.

Eventually all three got out and one of the girls told her mum who called the police.

Mr Ingram said this description of events was not contested by the defence who had been unable to get instructions from Baker.

The jury, charged solely with ascertaining the facts, decided that Baker had committed the rape and sexual assault and he was remanded for psychiatric reports.

Baker has been in England since 2002 and was jailed for one month in 2004 for an assault on a young girl.

After considering the psychiatric reports, Judge Patricia Dangor made a restriction order under the Mental Health Act and further ordered that Baker should remain on the sex offenders' register for life.