Sri Lanka's Tamil Tigers have carried out their first aerial attack, bombing a military base by the international airport north of the capital, Colombo.
Three air force personnel were killed, officials say, and 16 people injured when the bombs hit a parking area for planes and helicopter gunships.
The international airport - which was not damaged - was closed briefly.
Tiger rebels attacked the airport and base in 2001, killing 18 and wiping out half of the national airline fleet.
The Katunayake airbase and the civilian airport share the same runway.
The Tigers said that goverment planes retaliated on Monday, carrying out four raids in the north of the island. They said civilian areas were hit, but there were no casualties.
'More to come'
A statement from the Tamil Tigers, carried by the pro-rebel Tamilnet website, claimed responsibility for the attack on the military base, which is 30km (20 miles) north of Colombo.
The government said one plane was used. The rebels said two aircraft took part and that both planes returned to rebel-held territory safely.
"It is a measure to protect Tamil civilians from the genocidal aerial bombardments by Sri Lankan armed forces. More attacks of the same nature will follow," said the rebels' military spokesman, Rasiah Ilanthirayan.
Air force officials said no planes were hit, damage to the military facility was "minor" and that a search operation was under way.
The BBC's Roland Buerk in Colombo says the confirmation that the rebels now have an air capability confirms government suspicions that they had been smuggling in aircraft parts to be assembled in areas of the island they control.
One international airline, Cathay Pacific, announced that it was suspending flights to Colombo.
The authorities have set up an investigation into how the Tigers could have flown planes for more than 200 kms (125 miles) undetected.
The Tigers have released photos of planes and personnel they said took part in the raid.
"No terrorist group in this part of the world has any air capability," government minister Jeyaraj Fernandopulle told journalists in Colombo.
"This is a clear threat to the security of the whole region."
The raid on the air force base took place at about 0045 on Monday (1915 GMT Sunday).
The wounded air force personnel were treated at a military hospital
Flights in and out of the civilian airport were cancelled and roads cordoned off but no civilians were wounded and the runway was not damaged.
Neil Butler, a British passenger at the airport, was inside the terminal building when the attack happened.
"I heard a large thud and we all went to the window. There was a long silence and then several more explosions followed by machine gun fire," he told the BBC News website.
"The staff ran for the exit followed by the passengers. When I arrived downstairs in the check-in area a large crowd was running in a panic from the entrance where there had been more machine gun fire."
He said: "I saw what looked like kind of fireworks in the sky, like a series of red flashes. But I didn't see any aircraft going over."
The air force base, which adjoins the country's only international passenger airport, houses some of the aircraft used in recent air strikes against Tiger rebel bases in the north.
Air force officials said damage to the military facility was "minor"
Despite a ceasefire still being in place on paper, Sri Lanka has been sliding back towards civil war, with more than 4,000 people killed in the past 15 months, our correspondent says.
The rebels have been fighting the armed forces of the predominantly Sinhalese government for much of the past 20 years.
They want to establish an independent homeland for the minority Tamils in the north and east of the country, to be called Tamil Eelam.
About 65,000 people have been killed and one million displaced by the fighting.