* Rescued couple are in good health, police say
* President Santos apologizes to Spanish tourists (Adds police comment, details on rescue)
Colombian police early on Saturday rescued two Spanish tourists held captive by a criminal gang for nearly a month in northern Colombia, finding them sleeping in hammocks, and two men collecting a ransom were arrested in Spain, police officials said.
Maria Concepcion Marlaska, 43, and Angel Fernandez, 49, were seized on May 17 while traveling by car to the popular tourist destination of Cabo de la Vela on Colombia's northern peninsula.
"They are free and in good health," Colonel Elber Velasco, commander of La Guajira province police, told reporters. "It was a lightning rescue that required very important intelligence, an operation that did not require the use of weapons."
As part of a coordinated effort with Spanish authorities, a ransom worth 500,000 euros ($667,000) was paid in Madrid, General Humberto Guatibonza, head of Colombia's anti-kidnapping police, told reporters.
Spanish police later arrested the two bag-men, one Spanish and one from Syria, he said. The cash was recovered.
The tourists were freed just after midnight near the city of Maicao on a stretch of land which juts into the Caribbean Sea and borders northwestern Venezuela.
Police officials said no arrests were made during the rescue and gave no other details about the operation beyond saying the couple were found sleeping in hammocks.
The couple were held in the homes of several Wayuu Indians close to the border with Venezuela. They were chained at times, according to Velasco.
"The criminals moved them from place to place in order to disorientate them and make them feel that they were at times in Colombia and at times in Venezuela," said Guatibonza.
Marlaska and Fernandez were driving in the desert-like La Guajira province when they were stopped in a robbery attempt, Guatibonza said. When the robbers realized they were foreigners, they decided to take them captive.
President Juan Manuel Santos said on his Twitter account that he spoke to them after their release and apologized for their ordeal.
FARC BLAMED FIRST
The Revolutionary Armed Forces of Colombia, the country's biggest rebel group, last month denied accusations that it was holding the tourists, but Spanish news reports said the kidnappers had identified themselves as members of the Marxist-led guerrilla group when they contacted the family of the victims to demand the ransom.
The FARC and Colombian government began talks in November to try to end a war that began with the rebel group's formation in 1964 as a communist agrarian reform movement.
The FARC last year halted the taking of hostages and has repeatedly said the order was being followed by the entire rebel force.
The group has a history of kidnapping to raise money for its struggle against the government, but rebel leaders called a stop to the practice to encourage the peace process.
It is not unusual for criminals to claim kidnappings or other actions in the FARC's name.