Jos Brech was identified as a suspect after the Netherlands' biggest ever DNA harvesting operation, which included his relatives.

It gave police a vital clue linking him to DNA on Nicky Verstappen's clothes.

Extradition proceedings for the former scout master are under way.

"Jos B, 55, a suspect in the death of Nicky Verstappen was arrested in Spain on Sunday afternoon. He was taken into custody and will be handed over to the Netherlands," said a statement from police in Limburg, the southern Dutch province where the boy disappeared.

The arrest follows a public appeal last week, during which detectives shared photographs of the suspect. A Dutchman living in Spain recognised the man in the photos and sent a tip-off to police.

Nicky, then aged 11, was at a summer camp in August 1998 when he vanished from his tent. His body was discovered in the forest the following day.

Jos Brech, who lived nearby, was reported missing earlier this year, following the largest DNA testing project ever in the Netherlands.

One of the only pieces of evidence in the case was foreign DNA discovered on Nicky's clothing.

 Jos Brech (in green) was arrested near Barcelona

More than 14,000 men voluntarily gave DNA samples to the investigation - none of whom were suspects.

But by comparing the samples, it could be determined if a relative of the donor was a match, narrowing the search.

A killing that shocked the Netherlands

By Anna Holligan, BBC News, The Hague

This murder mystery has horrified and captivated the Dutch for two decades.

Nicky Verstappen, the freckle-faced schoolboy, was adopted as a symbol of an unfathomable, faceless threat to our children.

Now the prime suspect in his murder is in custody in Spain, and a European arrest warrant issued last week is expected to facilitate his return to the country where the grotesque crime was committed.

The Netherlands is buzzing with a desire for justice, and in some cases revenge.

If Jos Brech denies the charges, the challenge for prosecutors will be to ensure emotion does not affect the suspect's right to a fair hearing in court.

Jos Brech is seen here in police handout photos

Mr Brech did not participate in the call for voluntary DNA samples.

He was recorded as having passed the scene of the crime back in 1998, walking by a few days later shortly after midnight. He was stopped by police and later interviewed, but had been thought to be an innocent passer-by.

He had travelled to the Vosges area of eastern France last autumn and was reported missing by his family in April. He was known to be a expert in bushcraft, capable of staying in wilderness areas for long periods of time.

After he was reported missing, police examining his home discovered he was a 100% match for the DNA found on Nicky's body.

Nicky's mother Berthie told Dutch TV on Sunday night said the family did not dare believe that the arrest would come so soon after the police appeal on 22 August. "We hope there'll be quick answers now to all the questions we have," she said.

Spanish police were tipped off by a 48-year-old Dutchman who said he had seen him in the village of Castelltercol, an hour's drive north of Barcelona, and spoken to him in July.

"He'd been living in a tent in the woods, close to a house that several people have visited for years. It's a sort of commune where I had lived for ages too," the man told the Telegraaf newspaper.

A leading defence lawyer said he was prepared to take on the case on Jos Brech's behalf as there were traces of DNA from other people on the body as well.

 Mr Brech was reportedly detained when he went out to cut firewood