Defence Secretary Gotabhaya Rajapakse said the military had cleared a route for people fleeing the island's embattled north, where troops are advancing on the rebel capital of Kilinochchi, 330 kilometres (205 miles) north of Colombo.
"We plan to give passage to people from Kilinochchi to come to (government-held) Vavuniya.
We're dropping leaflets from the air, encouraging people to leave, giving details of routes to take to safety," Rajapakse said.
Nearly 135,000 people have been driven from their homes because of fighting between government forces and Tamil Tiger separatist rebels in the past two months, according to UN aid agencies.
"It's better for civilians to come to government-cleared areas so we can start to resettle them faster," said Rajapakse, the younger brother of Sri Lankan President Mahinda Rajapakse.
His comments came as the defence ministry