Washington ( CNN ) -- The U.S. government said Wednesday it is holding a Somali man on immigration violations , but gave no indication why the man was deemed to be a threat to a commercial jet that was denied permission to overfly the United States on Sunday . However , the brother of Abdirahman Ali Gaal , the detained man , said U.S. officials may be suspicious because of Gaal 's outspoken views about U.S. policy in the Middle East , his frequent comments on an Internet website , and his recent travel to Mauritania in northern Africa to study Islam . Abdifatah Gaal described his brother as `` confused '' by the detention because he had been assured by U.S. authorities while overseas that there was no impediment to his return to the United States . The case of Abdirahman Ali Gaal came to a head Sunday when U.S. authorities denied permission for the Aeromexico flight he was on -- traveling from Paris , France , to Mexico City , Mexico -- to overfly the United States . The flight was diverted to Montreal , where Canadian officials took custody of Gaal before turning him over to U.S. officials Tuesday . U.S. officials have since said that Gaal was on the `` no fly '' list , compiled by the government , of people banned from flying in the United States . Matthew Chandler , a Department of Homeland Security spokesman , said Wednesday that Gaal was questioned by U.S. officials . `` In the course of that interview process , he was determined to be inadmissible to the United States and is currently being detained pending immigration proceedings , '' Chandler said . Gaal admitted to having committed fraud when he applied for refugee status in Canada in October 2008 and to abandoning his `` legal permanent residency '' status in the United States by departing the U.S. for more than 10 months and applying for refugee status in Canada , a U.S. official told CNN on condition of not being identified by name . Immigration issues of that sort , however , do not typically put a person on the `` no fly '' list , which includes about 6,000 people , the official acknowledged . U.S. officials declined to provide any further information about the matter . Gaal 's brother , contacted Wednesday by CNN , said Gaal had strong political beliefs but has insisted he had done nothing wrong . Abdifatah Gaal said his brother was critical of U.S. policies in the Middle East and aired his views on Paltalk , which hosts Internet chat forums . Several months ago , he said , his brother went to Mauritania in northern Africa to study Islam . While in Mauritania , Gaal received a call from his wife in Toronto , saying she had been visited by Canadian police looking for him . Gaal then went to the U.S. Embassy in Mauritania and was told there was no impediment to him returning home , according to his brother . Gaal also called the FBI to check on his status , his brother said . Gaal flew to Paris and on to Mexico City , and intended to travel to Seattle , Washington , where their mother lives , his brother said . Abdifatah Gaal said his brother 's arm was broken when he was removed from the aircraft in Montreal , even though , he said , Gaal did not resist . He said the family is trying to hire an immigration attorney to represent his brother .
Man triggered weekend diversion of an Aeromexico flight . Brother says the detained man was told he could return to the United States . Man was on the `` no fly '' list compiled by the U.S. government .