"This is a direct impact of the attacks. There were a lot of cancellations," said Kishu Gomes, chairman of the Sri Lanka Tourism Development Authority told Reuters.
Foreign visitors in April fell to 166,975 compared with 180,429 in the same month a year ago, marking the single biggest monthly slump since the end of a civil war a decade ago.
More than 250 people were killed, including 42 foreign nationals, when suicide bombers attacked churches and luxury hotels across the Indian Ocean Island on April 21.