By Gustavo Palencia

TEGUCIGALPA (Reuters) - Five Syrian men detained in Honduras carrying forged Greek passports traveled through multiple countries before they were stopped, officials said, raising questions about how they were able to move through border controls with such apparent ease.

Honduran officials said on Thursday the five, including four students, do not belong to "any terrorist cell" and were fleeing war at home in a bid to reach the United States.

The five traveled to Honduras via Turkey, Greece, Brazil, Argentina and Costa Rica, the officials said.

"We got lucky on these guys. Think about the ones we didn't' catch," said a U.S. government source familiar with their case.

Their case has sparked alarm among some U.S. lawmakers following reports that at least one of the attackers involved in the suicide bombings and shootings in Paris last week may have slipped into Europe among migrants registered in Greece.

"This is a serious concern," Republican Senator Ron Johnson, chairman of the Senate Homeland Security Committee, told a hearing.

The five men, who are aged between 19 and 30, were part of a wider group of seven Syrian nationals who acquired forged passports in Brazil and then went by land to Argentina before heading north, the U.S. source said. The source also said there was no evidence to suggest the men were militants.

Honduran officials have offered a slightly different account, saying the passports were stolen in Athens.

Costa Rica detained an eighth Syrian, a woman, on Thursday, who had also been traveling on a Greek passport, officials said.

TRIPLE FRONTIER

The five Syrians detained in Honduras took advantage of the porous Triple Frontier near Iguazu Falls, a well-traveled tourist destination where Brazil, Argentina and Paraguay meet, the U.S. source said. The three countries belong to the Mercosur customs bloc, where you can cross borders with simple identity documents rather than passports.

The U.S. source said it appeared they spent most of their time in Brazil and then used a "human smuggling cell" to aid them on their trip north. He gave no details as to how they had traveled, whether by land or air.

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Another U.S. government source and local human rights officials in Honduras who had spoken to the men said Guatemala, not the United States, was their intended destination, although that seems an odd choice given so many Guatemalans are trying to leave their country to settle in the United States.

Whatever their final destination, it is unclear why the men were forced to take such a circuitous route that could have ultimately, in one scenario, taken them through a lawless region of Mexico controlled by drug cartels.

Five of the men were detained on Tuesday in the Honduran capital, Tegucigalpa, on arrival by air from Costa Rica, police said. They said passports had been doctored to replace the photographs with those of the Syrians.

The Honduran immigration department named the five as: Majd Ghanout Kousa, Fady Freej Shehada, Mazen Mikhail, Lourans Samaan and William Ghanem. It said they were from two Syrian cities that have been racked by violence: Homs and Hasaka.

One of the U.S. government sources said the five had arrived in Brazil from Turkey about a week ago. They then appear to have traveled from Brazil to Argentina and then on to Costa Rica, although it is not clear how they traveled there. A Honduran official said the five had spent several days in Costa Rica before flying into Honduras.

A third U.S. government official said it appeared the five traveled to Honduras because they believed that border controls would be lax there. However, they were arrested because their passports were so obviously forged.

The five may have chosen Brazil as their port of entry into Latin America because the country is seen as more hospitable to Syrians. It recently extended a two-year refugee visa program for Syrians fleeing their civil war, one of the signature humanitarian efforts of President Dilma Rousseff’s otherwise modest foreign policy.

The country has taken in nearly 2,100 Syrians, a quarter of its overall refugee population over the past two years. About 6,000 more were issued visas but have not made the long journey to Brazil.

Last month, however, Brazil detained eight Iraqi nationals who police said were traveling on false Greek passports they had obtained in Turkey.

PARAGUAY DETAINS SYRIAN

A sixth man was turned away from Honduras on Friday on arrival by plane from El Salvador, and was sent back, Honduran officials said. However, El Salvadoran officials say they have no record of this.

In Paraguay, police detained a seventh Syrian man who was traveling on a stolen Greek passport. A Paraguayan state prosecutor identified the man as Abd Al Elah Khallo from Hasaka.

"The Syrian people are very good. There are foreigners who are not from the country who are doing terrible things," the Syrian told Paraguayan television station Telefuturo, bursting into tears as he recalled a mortar that killed a young boy from his neighborhood.

He said he had lived in Turkey for a year before heading to South America, and was aiming to head to London via Mexico.

The U.S. government source said the man had been caught because his fake passport was missing some of the required vaccinations.

Separately, members of two Syrian families turned themselves in to U.S. authorities in Laredo, Texas, at the Mexican border, U.S. Homeland Security officials said on Thursday. Two men, two women and four children were handed over to immigration officials for processing.

At least nine undocumented Syrians were caught by Mexican authorities between January and September of 2015, according to immigration statistics from the Mexican interior ministry. During the same period last year, eight undocumented Syrians were apprehended by Mexican authorities.

According to the U.S. Department of Homeland Security, around 95 percent of some 662,483 people detained along U.S. borders in the 2013 fiscal year were citizens or residents of Latin America or the Caribbean. Only 4.5 percent come from the rest of the world, but it was unclear how many of those hailed from the Middle East.

(With reporting by Hugh Bronstein in Buenos Aires, Daniela Desantis in Paraguay, Caroline Stauffer in Brazil and Gabriel Stargardter and Joanna Zuckerman Bernstein in Mexico City and Julia Edwards, Mark Hosenball and Andy Sullivan in Washington; Editing by Simon Gardner and Ross Colvin)