Sri Lanka Customs officials are keeping a close watch on passengers bound for Chennai and Mumbai from the Bandaranaike International Airport in Colombo to check growing incidents of gold smuggling.Spokesperson of Custom department, Leslie Gamini told the media that investigations are underway to find out how the 56 Sri Lankans arrested in India were able to smuggle gold from Sri Lanka. He added that the Sri Lankan government is in touch with Indian authorities regarding the case.