The Spanish coastal resorts have been dubbed the "Costa del Crime" since the 1970s, because hundreds of wanted British criminals are thought to be living there. The charity Crimestoppers has set up a hotline to help UK police forces track them down.
Criminals can be attracted by the Spanish lifestyle and weather
Crimestoppers is now operating outside the UK for the first time and hundreds of people have called its free phone line.
Information given to Crimestoppers last month has already led directly to the arrest of one man, a suspect on the most wanted list issued by British police, on 3 December.
The man, who was living in the Murcia region, not far from Alicante, is now awaiting an extradition hearing.
He was wanted in connection with the smuggling of 568kg of cannabis resin from Spain into the UK.
Britons trying to evade the criminal justice system often flee abroad, believing they can remain anonymous.
But that is now becoming more difficult in Spain.
A photograph of a man awaiting extradition appeared in local newspapers up and down the Costas as part of an appeal by Spanish Crimestoppers, in conjunction with the police in the UK and Spain, called Operation Captura.
"It's primarily about helping UK enforcement agencies to locate people who have gone to ground in Spain," says Dave Cording, director of operations at Crimestoppers.
"The most important factor is that each and every one has a European arrest warrant out against them.
"Spain is an attractive place to go and hide because of the weather and the lifestyle."
Crimestoppers is an independent charity, and not part of Britain's police service. Its hotline is free and confidential.
British ex-pat James Herbert now lives near Pilar de la Horadada, about 30 miles from Murcia.
He used to be a police officer in Britain and helped set up Spain's first Neighbourhood Watch scheme.
"Because Crimestoppers is confidential, the police here and in the UK will get far more co-operation than ever before," he said.
"It's not a big community, and it's natural that residents are worried about reprisals."
Spain became a popular destination for Britons on the run after the collapse of the extradition treaty with the UK in 1978.
Ronnie Knight, the former husband of the actress Barbara Windsor, spent a decade on the Spanish Costas evading British justice.
Ronnie Knight faced handling charges on his return from Spain
He eventually returned to serve seven years in prison for his involvement in the 1983 £6m Security Express robbery.
A new extradition treaty with Spain was introduced in 1985.
And two years ago European arrest warrants came into effect making it far easier to bring suspected criminals back to the UK.
Lorenzo Martinez heads the Fugitives unit of the Spanish police.
He says wanted British criminals still head for Spain believing they can hide among the large ex-pat communities.
It is thought 350,000 UK citizens live in the Costa del Sol alone.
In contrast to the old generation of criminals, who used to go to retire, the new entrants are using Spain as a base for operations in Britain.
Sipping coffee in the Dia y Noche Bar in Pilar de la Horadada, British ex-pats said they were not surprised to hear that they could be living next door to a wanted criminal.
Ray went to live there from Norwich.
"If people commit a crime in the UK, that is jump bail or are wanted for a serious crime, they're hoping that if they come here they won't be recognised," he said.
"But if Crimestoppers can liaise with the Spanish police and publish the photographs of these people, then hopefully their days are numbered out here."
Lucinda, who runs a clothes shop in nearby Cabo Roig near the town of Torrevieja, says:
"The English community is small. If there are people here who shouldn't be, I think they'll be caught.
"You never know who you're talking to, it could be an armed robber or a murderer.
"I find I don't actually trust anybody out here."
Crimestoppers has published information on 20 wanted British criminals thought to be in Spain.
They are being sought for serious crimes including armed robbery and murder.
A reward of £30,000 is also being offered for information leading to the arrest of Francis Hurley, a convicted murderer and armed robber who escaped during a prison transfer in 1994.
Dave Cording says the hundreds of responses to Crimestoppers so far have given Spanish and British police "valuable information".