"It is not a cyclone at the moment but there is a possibility of a cyclone within the next 24 hours," department deputy director Lalith Chandrapala said.
Alerts were being sounded on radio telling people still trying to come to terms with the tsunami devastation to be "cautious and vigilant," he said. A low pressure system had developed in the Bay of Bengal around 300km southeast of the town of Hambantota, Chandrapala said.
"There is no immediate threat to Sri Lanka but if it develops into a cyclone then we will issue a cyclone alert."
Chandrapala said the department had cautioned all government offices and police on the southeast and eastern coast, especially in districts such as Ampara and towns like Galle, Matara and Hambantota.