The fire at the power station was quickly extinguished
Suspected Tamil Tiger rebels have carried out air strikes on oil tanks near the capital, Colombo, and in north-western Sri Lanka, the army says.
The attack in Colombo led to the sound of anti-aircraft fire reverberating across the city, parts of which were blacked out as a precaution.
The army says that a "terrorist aircraft" dropped two bombs near the military base in the town of Mannar.
The Tigers have not claimed responsibility for either attack.
The group has boasted air strike capability since the first mission of what they call their Tamil Eelam Air Force, or TAF, in March 2007.
The army says that a fire in the Colombo power station - near its oil storage tanks - was quickly extinguished and there were no injuries.
They say that the Mannar attack was on the military headquarters and one soldier was injured.
No damage was done, they added, saying that anti-aircraft guns returned fire at the plane.
The Tamil Tigers are on the defensive in the north
Shortly afterwards the Colombo strike the sound of heavy guns was heard throughout the city - 250km (155 miles) to the south - as people stood in the streets watching.
"The aircraft dropped bombs in Colombo near the oil storage tanks," a military source said.
Analysts believe an air attack by the rebels last year opened a new dimension in Sri Lanka's decades-long civil war.
At the time, a Tigers spokesman described it as "a measure to protect Tamil civilians from the genocidal aerial bombardments by Sri Lankan armed forces".
The military says the Tigers' air wing has three two-seater Czech-made Zlin-143 aircraft fitted with homemade bombing equipment.
The BBC's Sri Lanka correspondent, Roland Buerk, says the latest air raids come as the Tigers are seen to be facing setbacks on the ground.
In recent months they have been driven from many towns and villages along the coast in the north-west and their stronghold of Killinochchi is under attack from the army in the north.
At least one senior government figure has talked of defeating the rebels militarily within two to three years.
The rebels have been fighting for a separate homeland for a quarter of a century and about 70,000 people have been killed in the violence.