Al Jazeera's David Hawkins, reporting from the northern Vavuniya district, said the camps for Sri Lanka's displaced appeared to meet international standards.
"Holmes is here to see whether or not the food and the shelter are adequate ... and it seems to me that they are," he said
"But there's another question, as to whether or not people have freedom of movement."
The Sri Lankan government has been criticised for limiting free movement of the displaced people, preventing them from leaving the camps.
Officials, however, say its a largely bureacuratic issue, promising they will be allowed to leave the camps once they have received government identification cards.
Rights groups have also accused the government of firing on fleeing civilians.
In a statement on Friday, Human Rights Watch accused the Sri Lankan military of shelling hospitals and so-called safe zones in the north in recent weeks.
It said that about 2,000 civilians had been killed by the fighting in the last month alone, and called on the government to end indiscriminate artillery fire.
"This 'war' against civilians must stop," James Ross, the legal and policy director at the New York-based rights organisation, said.
Sri Lanka's government has denied responsibility for civilian deaths, instead accusing the Liberation Tigers of Tamil Eelam (LTTE) of using them as human shields.
Human Rights Watch also accused the LTTE of shooting at fleeing civilians.
The Tigers have denied holding civilians as human shields against the mounting military offensive or shooting at those who flee.
The International Committee of the Red Cross, which has a limited presence in the areas of fighting, says "hundreds" of civilians had been killed in the crossfire in recent weeks.
After a meeting with Rohitha Bogollagama, Sri Lanka's foreign minister, Holmes said he was "concerned about reports of heavy casualties to the civilian population".
Meanwhile, the Sri Lankan defence ministry claimed it had captured diving equipment used by the LTTE after five hours of fighting at the village of Ampalavanpokkanai.
The Tamil Tigers have been fighting since 1983 for an independent state for minority Tamils after decades of marginalisation by the Sinhalese majority.