The US Homeland Security has apologised to Civil Aviation Minister Praful Patel who was questioned by the immigration authorities in Chicago as his name and date of birth happened to match with that of a person on America's watch-list.

Patel, who was in Chicago on a private visit and flew to Montreal for attending an official engagement, was stopped and quizzed at the O'Hare airport. The minister was asked why he was visiting the US and whether he had stayed in the country earlier.