Two Sri Lankan airline flights were diverted to India, Civil Aviation Authority Chairman Paddy Mendis told LBO.
However the airport has since been re-opened and some aircraft including a Cathay Pacific flight has landed.
Airforce aircraft were scrambled to search for rebel aircraft in Puttalam and nearby Kalpitiya, officials said.
Colombo city was blacked out by the power utility.
Air Force spokesman said anti-aircraft fire was activated as as a defensive measure.
The Tamil Tigers bombed the Katunayake airbase in March in their first air raid.
The Tiger air wing also flew a sortie to the Palaly military complex in the northern Jaffna peninsular Tuesday, but were not able to reach the airport.
However si