Buenos Aires, Argentina - Police have briefly detained dozens of Muslim missionaries from the Arab world and South Asia in recent months, acting on tips from Spanish and Italian officials investigating terrorist attacks in Europe.
Argentine newspapers reported that 26 members of Jamaat Tabligh, an Islamic missionary sect, had been held, questioned and released.
European investigators suspect Jamaat Tabligh of involvement in the March 2004 Madrid train bombings that killed nearly 200 people, according to a report in the La Nacion newspaper.
The newspaper said the missionaries entered Argentina earlier this year on a possible recruitment mission.
Felipe Sola, governor of the state of Buenos Aires, confirmed that seven Jamaat Tabligh adherents from Qatar and Egypt were detained three months ago in his jurisdiction.
Officials held the men for several hours, retaining their passports but ultimately releasing them because they had not violated the law, Mr. Sola said. Malaysian, Pakistani and South African nationals were also detained in other parts of the country.
Attempts to contact representatives of Jamaat Tabligh were unsuccessful.
The sect, founded in India in the 1920s, preaches nonviolence and rejects all political involvement.
However, it advocates an ascetic lifestyle mimicking that of the prophet Muhammad in 7th century Arabia -- a similarity with al Qaeda and other Muslim terrorist groups.
It sends missionaries all over the world, and some Western-born militants -- such as American John Walker Lindh, who was captured by American troops in Afghanistan -- are said to have received their introduction to Islam from Jamaat Tabligh.
Mr. Sola said national authorities were monitoring the group, which intelligence analysts speculated are targeting the country's 700,000-strong Muslim population because Argentine nationals draw less suspicion at international borders.
U.S. officials have raised concerns about the group.
"Individual members of legitimate organizations, such as Jamaat Tabligh, may be targeted by al Qaeda in an effort to exploit their networks and contacts here in the United States," FBI Director Robert S. Mueller III told the Senate Select Committee on Intelligence in February.
The La Nacion report, citing unnamed government sources, said Spanish officials had warned their Argentine counterparts that "Jamaat Tabligh has often been an entry door in a country al Qaeda has used."
Hector Icazuriaga, chief of the Argentine Secretariat of State Intelligence, known by its Spanish acronym SIDE, told reporters that Jamaat Tabligh was a priority for the agency, which was keeping the group's members under close observation.