NEW DELHI - A total of 15 Indian tourists died in a boat tragedy in Vietnam on Saturday, confirmed a senior official in New Delhi.

There were 36 people on board the ill-fated speedboat, which capsized off Vietnam's Phu Quoc Island earlier in the day.

Arja Srikanth, special commissioner and special representative for the Andhra Pradesh government in New Delhi, said 21 survivors were taken to hospitals, while two remain in critical condition.

The Indian authorities were closely monitoring the situation in coordination with their Vietnamese counterparts, he said.

Adverse weather conditions, rough seas and a possible mechanical malfunction in the speedboat were said to be the possible causes leading to the mishap.