Alex, who emerged as the spokesman for the 255 Sri Lankans whose boat was detained last month en route to Australia, is Kulaendrarajah Sanjeev, a 28-year-old who worked out of a base in India, the foreign ministry said in a statement.
The man, who led an abortive hunger strike demanding that those on board be granted refugee status, was expelled from Canada in 2003, the statement said.
"Alex had been involved in human smuggling for a long time and it is believed that his office is based in India," the statement said.
"His brother who is now in Canada is also involved in human smuggling" and is being sought by Canadian police, the statement added.
The ministry did not give further details.
Alex emotionally denied the allegations when contacted by AFP by telephone in Indonesia, saying they were a ruse to discredit the boat people and distract from widespread rights abuses in Sri Lanka.
He neither confirmed nor denied the identity given by the Sri Lankan government,