Huge numbers of civilians fled from the final battles
A senior Sri Lankan Tamil political leader has urged the government to resettle civilians back to their homes as early as possible.
V Anandasangaree described conditions in camps for civilians displaced by the country's war as "horrible".
The head of the Tamil United Liberation Front (TULF) said hundreds of thousands faced misery and hardship.
He said there were food, health and sanitation problems in camps set up for Tamil civilians in northern Sri Lanka.
The United Nations says nearly 300,000 people have been displaced by recent fighting between government forces and Tamil Tiger rebels.
The civilians have been housed in various camps, most of them in Menik Farm, near the northern town of Vavuniya.
The Menik Farm camp site, which is described by the UN as the world's largest displacement camp, houses around 220,000 people displaced by the fighting.
Mr V Anandasangaree, the TULF leader, is one of the few remaining long-serving moderate Tamil political leaders in Sri Lanka. He has strongly supported the government's stance against the rebels.
"From the reports I get from the people [in the camps] they are good in some areas and horrible in many," Mr Anandasangaree told the BBC.
V Anandasangaree has been a critic of the Tamil Tigers
"Health, water and sanitation situation is horrible. Many people are having skin diseases as they didn't get a chance to have a shower for days because of water shortage.
"Pregnant mothers and newborn babies go through a harrowing time in the camps due to scorching heat," he said.
The Sri Lankan government accepts that conditions in some of the camps are not ideal but says facilities have been improved in many other camps. It says more land is also being allocated to build new camps to decongest those already full.
The United Nations and other aid agencies have also demanded better access to the camps to carry out humanitarian work.
Sri Lanka's government is wary of aid agencies and has complained that the agencies had helped the Tigers in the past.
Sri Lanka says it plans to resettle most of the refugees within six months.
Mr Anandasangaree, a well-known critic of the Tamil Tiger rebels, the LTTE, also faulted the government for viewing every Tamil civilian in the camps as a possible Tamil Tiger suspect.
Sri Lanka has said it needs time to weed out potential Tamil Tiger infiltrators hiding in the camps.
"The civilians risked their lives while fleeing from the LTTE-held areas as the rebels were shooting at them. If the government suspects such people as Tamil Tigers, then the entire population of the two districts - Kilinochchi and Mullaitivu - should be the suspects," he said.
"Then the government will never solve the problem."
Sri Lankan officials say they have been overwhelmed by the sudden arrival tens of thousands of civilians from rebel-controlled areas since the start of the Sri Lankan military's final battle against Tamil Tigers a few weeks ago.
The government says it also requires help from the international community for post-war resettlement and reconstruction.
The TULF leader also challenged the official view that de-mining needs to be carried out before the resettlement of civilians can begin in the north.
"The theory that the area is heavily landmined cannot be accepted because I am in touch with a number of people. So, when I ask them they tell me where the landmines are placed. They are local people. According to them, 75% per cent of the area is not at all landmined," the Tamil leader said.
Mr Anandasangaree said Sri Lankan security forces were doing a commendable job in carrying out relief work for the displaced civilians, but said that was not enough.
"The government cannot address the problem fully on its own because of the size of the displaced population."