The Tigers mounted a pre-dawn raid on oil facilities north of the capital on Sunday, their third such attack in a month using light aircraft smuggled into the country by boat in pieces, and the Air Force has been unable to shoot them down.
The Tigers have also targeted an air force base adjacent to the international airport, with which it shares a runway.
''Due to the prevailing situation, to minimise inconvenience caused to airline operators and passengers ... the airport will close starting from 9th of May between 10:30 p.m. and 4:30 a.m. the following morning,'' the duty manager at Bandaranaike International Airport told sources, asking not to be named.
Singapore Airlines and Malaysian Airlines are among carriers which have already rescheduled their flights to daytime hours as a security precaution.
The Liberation Tigers of Tamil Eelam (LTTE), who are fighting for an independent state for ethnic minority Tamils in the north and east of the Indian Ocean island, have vowed to conduct further air strikes as a two-decade war that has killed more than 68,000 people since 1983 deepens.