Police investigating the Madeleine McCann disappearance have been called in after a dad stopped a man abducting his three-year-old daughter on holiday.
The horrified dad caught the man, who is also believed to be British, as the child was being led hand-in-hand down an alleyway on the holiday island Lanazarote. He only saw her disappearing because of her flashing trainers.
The Metropolitan Police's McCann review team confirmed it was now working with the Thames Valley force over the case.
Police said they had arrested a man in London in the connection with the alleged kidnapping who will be questioned today.
A spokesman said: "A 62-year-old man has been arrested in connection with an attempted abduction in Lanzarote.
"He was arrested on suspicion of attempted kidnap and is currently in police custody."
The girl's dad last night told Madeleine's parents Kate and Gerry: "I hope we can help. The whole experience has been horrific - I hope something good can come out of it."
He confronted the suspect in Lanzarote at Las Cucharas shopping mall in Costa Teguise.
The 36-year-old, who does not want to be named, told The Sun: "I ran over and shouted at him. I then grabbed my daughter and he just kept his head down and walked off."
After making sure his girl was fine, he phoned police and went looking for the man. He spotted him apparently fondling himself at a nearby beach a few hours later.
The dad, who has three daughters, said: "He had a newspaper over his lap and his hand down his pants - there were three or four young girls playing on the beach.
"He jumped up and ran off. I gave chase and stopped him.
"I said, 'You'd better say something because I think you're a dirty pervert and I'm going to smack you.'"
The suspect spoke fluent English as he told the dad, of Milton Keynes, Buckingham, he had been on his holiday flight to the island and had intended to bring the girl to him.
The man, who slipped away, was white, with pasty skin and aged 40 to 55. He was around 5ft 8in tall, stocky, with short dark hair and a moustache.
Detective Constable John Swallow, leading the hunt, said: "We are working closely with Spanish authorities and Interpol."
The McCanns' spokesman Clarence Mitchell said: "Kate and Gerry are aware of the incident. It is very fortunate this child was found so quickly."
Madeleine disappeared from Praia da Luz on May 3, 2007.