Send them flowers: Code for murder Colombian style

The ringleader went by the name of "Rabbit", his deputy was "the Monster" and when the order to kill came it was coded: "If they won't pay, send them flowers."

Police this week arrested seven Colombians in Madrid who are suspected of running a "branch office of hitmen" set up to kidnap, maim and kill rival drug cartel members and to collect debts from their own drug traffickers.

After a sting operation code-named "Achilles" that lasted 16 months, officers from Madrid's Central Organised Crime Brigade moved in on the cell of assassins and seized an arsenal of weapons.

The gang had their headquarters in a Colombian restaurant in Leganes, a working-class suburb in the south of Madrid, where they met over lunches, dinners and afternoon coffees.

There they planned elaborate ruses to snare their victims, sometimes impersonating police officers or doctors, and they were found with an array of disguises including police uniforms, white medics' coats and a set of wigs.

Police moved in last week as the gang took delivery of a cache of weapons originating in eastern Europe that included several Kalashnikov rifles fitted with silencers, a 357 magnum revolver, two shotguns and a long-range rifle with telescopic lens.

During the raid, officers also seized electronic detonators, explosives and an anti-tank grenade launcher.

Investigators believe the gang was sent to Spain to collect debts and settle scores on behalf of Colombian drug cartels while also trying to forge an alliance with Mexican traffickers based in Spain's eastern city of Valencia.

It was the first time police had smashed a squad apparently sent to set up a permanent base in Spain, said Andres Dieguez, the head of the Central Organised Crime Brigade.

Previously, lone hit men had been sent over from Colombia to settle scores and protect their business in Spain, the main cocaine gateway into Europe, before returning to South America.

The gang were also in possession of containers of acid, which they are suspected of using to destroy the bodies of their victims and to ensure their identification would be difficult.

Among those arrested were the suspected leader of the cell, who went by the alias Conejo meaning rabbit and his right-hand man El Monstro, the monster, police said. They have not released the real names of those arrested.

The first was wanted by Colombian police and was involved in a feud with a rival gang of assassins in Colombia, believed to be responsible for killing his brother six months ago and his nephew earlier this month.

El Monstro was wanted on an international arrest warrant for other murders in his home country.

According to local media reports, some of the gang were former members of the paramilitary group, United Self-Defence Forces of Colombia. The gang is also suspected of touting for work from other criminals for which they offered to kidnap, maim or kill, in return for 50 per cent of the money owed by the target.

Among its victims was the sister of a drug criminal jailed in Spain who had outstanding debts to a cartel in Colombia. They were ordered to kidnap the woman until the convict could arrange payment.