"We are not involved in politics. We are involved in seeing that people are fed," said James Morris, executive director of the U.N. agency, who came to the island to assess the aid effort for victims of Asia's tsunami.
During his tour Morris met S.P. Thamilselvan, the political chief of the Tigers, the BBC reported Sunday.
WFP says it is trying to feed some 2 million tsunami survivors across the region, including up to 750,000 people in Sri Lanka, where nearly 31,000 people died.
Morris said WFP is providing food to 90,000 people in the rebel-controlled north, and the numbers are growing.
Last week U.N. Secretary General Kofi Annan was prevented from visiting the rebel-held area by the Sri Lankan government. Reportedly the government was afraid a visit by the U.N. chief would legitimize the rebels' demands.