COLOMBO, Sri Lanka, March 27 — A day after guerrillas bombed a military air base on the edge of the capital here, seven people were killed today when a pair of suspected rebel suicide bombers tried to drive a tractor loaded with explosives into an army camp in the country’s east.

The two suspected bombers were also killed in the explosion. At least 23 people were injured, including at least six children, according to the Sri Lanka Monitoring Mission, which monitors what is now effectively a defunct truce in the country.

Suicide strikes are a hallmark tactic of the rebel Liberation Tigers of Tamil Eelam. They have fought for over two decades for a separate ethnic Tamil homeland. However, the rebels did not immediately claim responsibility for the suicide attack today, which took place at the Chenkaladi military camp in Sri Lanka’s eastern Batticaloa district.

A government military spokesman, Upali Rajapaksa, said the bombers tried to enter the camp with a tractor loaded with around 200 kilograms, or 440 pounds, of explosives.

When they were intercepted by troops at a checkpoint, the bombers blew themselves up. Among those instantly killed was a 12-year-old boy, according to the military.

“They are showing signs of desperation,” Major Rajapaksa said of the rebels. “If they had managed to enter the camp it would be have been a disaster.”

The rebels claimed responsibility for the air strike on Monday, which was the first time they had used airpower to launch an attack.

In that attack, it remains unclear whether the air force detected the approaching aircraft on its radar since the rebels, known here as the L.T.T.E., were able to attack and escape unscathed.

The government said late on Monday that two separate inquiries were underway to determine whether there had been any lapses in security which may have helped the air strike.

“The security forces will now have to take into account the air threat factor of the L.T.T.E.,” Iqbal Athas, a defense analyst and a columnist with the Sunday Times newspaper here, said by email. “Now VIP homes, naval ships, frontline troops, ports, key military establishments all become vulnerable.”

The Tamil Tigers are a banned terrorist group in the United States, European Union, and elsewhere.

They were blamed for a suicide attack last year that narrowly missed the army chief, Lt. Gen. Sarath Fonseca. In that attack, a woman bomber managed to penetrate deep into the heart of the army headquarters in Colombo. The Tamil Tigers have taken responsibility for the suicide attack that killed the Indian Prime Minister, Rajiv Gandhi, in 1991.

Their back-to-back strikes this week follow a steady advance by the Sri Lankan military on rebel-held areas in the east, in what appears to be a bid to flush out Tamil Tiger bases along the country’s strategic eastern coast and reinstate government control there.

The government has been aided in its efforts by the emergence of a breakaway Tamil Tiger faction, known as the Karuna group, two years ago.

The renegade faction operates openly in government-held areas in the east. The government insists it has no control over it.

There is a political imperative to exercising control over the country’s eastern province.

The Tamil Tigers consider the east as part of their traditional Tamil homeland, whereas the ethnic Sinhalese-dominated government does not. Government officials have said they plan to hold elections in the east in the coming months.

In the meantime, the country’s east is suffering a dire humanitarian crisis caused by the conflict. In the last two months alone, fighting has driven an estimated 150,000 people from their homes. The total number of internally displaced people in the country today stands at more than 350,000.

New York Times