SANTO DOMINGO, March 19 (Reuters) - A Dominican Republic man who acted as legal adviser to a group of U.S. missionaries held for several weeks in Haiti on child kidnapping charges has been arrested in Santo Domingo, local police said on Friday.

Jorge Puello Torres, wanted by El Salvador as a suspect in a human trafficking ring, was detained at a car wash in the city late on Thursday, a spokesman from the Dominican Republic's police anti-narcotics unit said.

He was arrested in the Dominican Republic's capital on a warrant issued by Interpol, the international police organization.

U.S. and Dominican Republic authorities had been looking for Puello after El Salvador officials said they suspected him of being involved in running a human trafficking ring that recruited Central American and Caribbean women and girls and forced them to work as prostitutes.

The allegations emerged after Puello offered his services as a legal adviser to 10 U.S. Christian missionaries who were arrested by Haitian authorities late in January and accused of trying to take 33 children over the border into the Dominican Republic after the devastating Jan. 12 earthquake in Haiti.

Haiti and the Dominican Republic share the Caribbean island of Hispaniola.

Eight of the Americans, most of whom were members of a Baptist church in Idaho, were freed by a Haitian judge in February. A ninth was released on March 8.

Only the group's leader, Laura Silsby, remains detained and still under investigation in Haiti's capital Port-au-Prince.

The Americans denied any wrongdoing and said they had been trying to help children left orphaned and destitute by the Haitian earthquake. They said Puello had approached their relatives and church, offering his help.

It turned out that the children who were with the U.S. missionaries had living parents, many of whom testified they had voluntarily handed their offspring to the Americans in the hope they would be given an education and a better life.

The case threw a spotlight on fears that child traffickers could prey on vulnerable Haitian children after the quake. But it also distracted attention from international relief efforts to help more than a million survivors left homeless or displaced by the disaster.

Haiti's president has said the final death toll from the quake could reach 300,000.