A top United Nations envoy warned Myanmar Sunday not to backtrack on its ongoing reform program and said the civilian government should acknowledge its past human rights violations to allow the country to move forward.

Argentine Tomas Ojea Quintana, on his fifth visit to the country as a special expert on human rights, said he had seen signs of positive developments in the former Burma but more needed to be done before it could be regarded as concrete progress.

Serious challenges remain and must be addressed. There is also a risk of backtracking on the progress achieved thus far, Quintana said in a statement issued at the end of his fact-finding visit to Myanmar, which began on January 31.

At this crucial moment in the country's history, further and sustained action should be taken to bring about further change.

Myanmar's new government is comprised mostly of retired generals from the same regime that was accused of overseeing a catalogue of human rights abuses, from brutally crushing protests and jailing politicians to muzzling the media and forced labor, murder and rape by its military.

But a few months into his five-year term, President Thein Sein introduced a wave of reforms from mid 2011 that have not been seen in decades. The pace of change has stunned many observers and foreign governments, and sharpened the debate on if and when Western sanctions would be lifted.

TAINTED

Quintana said the reforms did not mean the new rulers' tainted record would be expunged and acceptance by the government serious rights violations had taken place would help toward long-term stability in the nation of 60 million people.

I must stress that moving forward cannot ignore or whitewash what happened in the past, he told reporters.

Thus, facing Myanmar's own recent history and acknowledging the violations that people have suffered, will be necessary to ensure national reconciliation and to prevent future violations from occurring.

Quintana met the ministers of border affairs, interior and defense, as well as the chief justice, the election commission and opposition leaders, including Nobel Peace Prize winner Aung San Suu Kyi, who will run in her first-ever election in April when she contests one of 48 by-elections for legislative seats.

(Reporting by Aung Hla Tun; Editing by Martin Petty and Sophie Hares)