YANGON, Myanmar — A United Nations human rights expert kicked off a weeklong visit to Myanmar Monday by focusing on deadly strife between Buddhists and Muslim Rohingyas that shook a western area in June. Tomas Ojea Quintana's met with Myanmar's minister of border affairs for a briefing on the situation in northwestern Rakhine state. At least 78 people were killed in communal violence there last month. Quintana plans to visit the area on Tuesday and told reporters he would reserve comment until after his trip. In a pre-arrival statement, Quintana mentioned the violence in Rakhine — which rights groups say mostly targeted the Rohingyas — as one of the “challenges” facing Myanmar despite its recent political reforms. Myanmar does not recognize the Rohingya as one of its ethnic groups and many in the country consider the Rohingya to be illegal immigrants from Bangladesh. The United Nations says there are about 800,000 Rohingya in Myanmar and considers them to be among the most persecuted people in the world. Quintana's evaluation is likely to be regarded as a yardstick for measuring reforms undertaken by elected President Thein Sein after decades of repressive military rule. Earlier in the day, the envoy visited Yangon's infamous Insein Prison, where he said he interviewed prisoners of conscience. His trip will also include meetings with opposition leader Aung San Suu Kyi and government officials. Quintana's trip comes just days after the United Nations warned that Muslim communities in Rakhine, particularly the Rohingya people, were being targeted by security forces. Earlier this month Amnesty International warned of “credible reports” of abuses — including rape and unlawful killings — by both Rakhine Buddhists and the security forces. According to official figures, at least 77 people were killed in the unrest, including eight killed by security forces. Of the more than 60,000 displaced, Myanmar officials said the vast majority — around 53,000 — were Muslims. Ten aid organization staff — six from the UN and four employees of Doctors Without Borders (MSF) — are among more than 800 people being held in relation to the unrest. Both sides have accused each other over the attacks, which flared up following the rape and murder of a local Buddhist woman and subsequent revenge killing of 10 Muslims on June 3 by a mob of ethnic Rakhines. Fears about the situation have spread across the Islamic World, with threats of violent reprisals against Myanmar from Pakistan to Indonesia. — Agencies