The Liberation Tigers of Tamil Eelam estimated 2,000 troops had massed on a beachhead a mile from the north-eastern garrison at Mullaitivu. "Troop reinforcements are now consolidating their position in preparation for a major counter-offensive," said the statement from London.
The army confirmed its planes were hitting guerrilla positions. The Tigers said that air force bombers, helicopter gunships and naval gunboats were attacking their positions but with few casualties.
"LTTE fighting units are well positioned with heavy weapons to meet the imminent offensive which might take place soon," the statement said. Troops recaptured the base on Wednesday after the camp was overrun by the Tigers last week. Both sides say hundreds died in the week-long battle, one of the fiercest in Sri Lanka's 13-year ethnic war.
Meanwhile, Sri Lankan police detained 27 suspected Tamil rebels for questioning after two bombs killed at least 78 commuters and injured at least 450 on a packed train in Colombo on Wednesday.
The state-run Observer newspaper said the suspects were held following a police raid in the predominantly Tamil district of Wellawette in Colombo. Police suspect the bombs were in three briefcases in the train.
The Tigers' statement from London said that the government was trying to whip up anti-Tamil emotions by blaming the guerrillas, fighting for a separate homeland for minority Tamils in the north and east.
"Even though the accusing finger is pointed by the government at the LTTE, there are interested parties within the Sinhala ruling establishment who feel the need to raise chauvinistic hysteria in order to facilitate the military option," it said.
"We also wish to reiterate that it is not the policy of the LTTE to attack civilian targets."