U.N. human rights envoy Paulo Sergio Pinheiro is continuing his visit to Burma by holding talks with leaders in the remote capital of Naypyidaw.
Wednesday morning, Pinheiro met with the top U.N. diplomat in Burma, Charles Petrie, as well as more than 20 members of the diplomatic corps.
Petrie said the special envoy was "disturbed" by the recent arrest of a prominent labor activist, Su Su Nway, whose whereabouts are unknown.
Later, Pinheiro held talks with foreign and information ministers. He also met with Labor Minister Aung Kyi, who is acting as a liaison between the military-ruled government and detained opposition leader Aung San Suu Kyi.
Pinheiro returns to Rangoon Thursday to complete his five-day trip.
Meanwhile, witnesses in Burma say three more activists were arrested while handing out anti-government pamphlets at a fruit market in Rangoon.
Burma's military government crushed pro-democracy protests in September, and Pinheiro is in the country to investigate how many people were killed and thrown in jail during the crackdown.
According to Burmese officials, 10 people were killed and nearly three thousand detained in the September crackdown. But diplomats and human rights groups say the true figures are much higher.
Pinheiro's visit follows that of the U.N. Secretary-General's Special Adviser Ibrahim Gambari.