Tomas Ojea Quintana's evaluation is likely to be regarded as a yardstick for measuring the reforms undertaken by elected President Thein Sein after Myanmar ended decades of repressive military rule.
The violence that flared last month between the ethnic Rakhine Buddhists and Muslim Rohingya has subsided, but human rights groups and Islamic nations say the Rohingya community faces ongoing abuse and needs protection.
Quintana visited two of the main sites of the June violence, the Rakhine state capital Sittwe and Maungdaw township, but declined to answer journalists' questions about what he found.
Myanmar does not recognize the Rohingya as one of its ethnic groups and instead considers them to be illegal immigrants from Bangladesh.
The United Nations says about 800,000 Rohingya live in Myanmar and they are among the most persecuted people in the world.
Quintana has made clear that investigating the conflict is a priority of his visit. Before his trip, he called the violence in Rakhine one of the "challenges" facing Myanmar despite recent political reforms.
The U.N. has a direct interest in the Rakhine issue because five workers for the world body's refugee agency are among 858 people still detained in connection with the unrest. Five other
The aid workers have been accused of taking part in the violence and "setting fire to villages," Border Affairs Minister Lt. Gen. Thein Htay told reporters.
Indonesia on Tuesday joined the countries expressing concern about the treatment of the Rohingya. President Susilo Bambang Yudhoyono said his country would engage diplomatically with Myanmar to try to stop the violence.
Indonesia said previously it would raise the matter at the Organization of Islamic Cooperation summit in Saudi Arabia scheduled for mid-August.