The pre-dawn attack in Mutur, in the eastern district of Trincomalee, comes amid escalating tension between the military and the Tigers over a rash of incidents the army blames on feuding between the mainstream rebels and a renegade faction.
The Liberation Tigers of Tamil Eelam (LTTE), who have accused the military of helping the breakaway faction mount attacks against its cadres, denied any hand in the incident.
"The hand grenade was thrown at a security point and a few shots were fired towards a centre for internally displaced people," said military spokesman Brig. Daya Ratnayake.
"Two soldiers are in a serious condition due to shrapnel," he added. The girl also received shrapnel injuries," he said. "Eight incidents have happened since yesterday -- seven grenade-throwing incidents and one firing incident -- all the LTTE's blame."
Police said none of the other 40 tsunami survivors living in the camp were hurt.
December's tsunami killed nearly 40,000 people along Sri Lanka's shores and tens of thousands of survivors are now living in camps for displaced or rudimentary temporary housing on both sides of the island's ethnic divide.
The Sri Lankan government last month agreed a long-awaited pact to share $3.0 billion worth of tsunami aid with the Tigers, a deal donors hope could help jumpstart talks to permanently end the island's civil war, in which 64,000 people died.
The Tiger's war for self-rule was pushed into limbo by a 2002 ceasefire, but peace talks stalled two years ago.
Complicating matters, the Tigers -- who are allowed to move through government areas under the truce -- have threatened to use armed escorts to protect their cadres against attack, a move that would violate the ceasefire and raise the spectre of possible confrontations.
The two week deadline the rebels have given the government to assure their safety expires on Thursday, though analysts and diplomats do not expect the situation to escalate.
- Reuters - Thomson Reuters Foundation
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