Some of the displaced who have headed to the Tamil Tigers' political capital, Kilinochchi district, had been on the run for months, the International Committee of the Red Cross (ICRC) said.
"Among those displaced... are people who have had to abandon their homes several times in the recent months," the ICRC said in a statement.
Access to food, shelter, sanitation and clean water was an urgent priority for those fleeing, the ICRC said.
Health facilities were "struggling to cope with the increased demand.
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"Many people have received basic humanitarian relief but as the number of displaced persons increases, so do their needs," said Anthony Dalziel, the ICRC's deputy head of delegation in Sri Lanka.
United Nations aid agencies working in the conflict-hit areas said 112,019 people had been internally displaced in the past two months and warned that "the figure is expected to increase.
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"The general security situation in Kilinochchi and Mullaittivu districts remains te