The United States urged Burma to address what it called worsened ethnic violence and to accept international monitors to ensure the fairness of closely watched upcoming by-elections.

“Yet at the same time violence in the Kachin state has worsened with reports of serious human rights abuses and violations of international humanitarian law,” said Michael Posner, the assistant secretary of state for human rights.

“Ultimately the ethnic violence is rooted in political causes and it will require negotiated political solutions on both sides to address the underlying grievances,” he said at the National Endowment for Democracy.

Burma’s nominally civilian government, which took over last year, has reached ceasefires with Shan and Karen rebels in an effort to end ethnic bloodshed that has gripped parts of the country since independence in 1948.

But bloody battles have taken place since June in Kachin state in the far north. Human Rights Watch in a recent report said that Burma’s army raped, tortured and killed civilians in ethnic minority conflict zones last year.

President Thein Sein has surprised even many critics by undertaking reforms and talks with minorities and the opposition. Democracy icon Aung San Suu Kyi is optimistic enough that she is seeking a seat in parliament in April 1 by-elections.

Posner said that the United States has spoken to Burma about letting in monitors to ensure an “open and fair election.”

“We have had those discussions and very much hope that the process will be open both to local monitors and to those coming from outside,” Posner said.

US senators who recently visited Burma including John McCain also said that they asked Thein Sein to accept monitors but had not received a commitment.

Suu Kyi’s National League for Democracy swept elections in 1990 but military rulers ignored the results and confined the Nobel Peace Prize winner to house arrest for most of the ensuing two decades.

Posner said it was unrealistic to expect Burma’s reforms to advance without a hitch.

“When ossified societies begin to loosen up, the process is neither linear nor smooth. That is why this administration is committed to a long-term engagement, one that both continues to push for reform and change while at the same time offering encouragement and support,” Posner said.

The Obama administration last month said it would move to restore full diplomatic relations with Burma for the first time in three decades. It has also voiced openness to ease its sweeping sanctions in return for more progress.

Bauk Gyar, an activist from Kachin state who is running in the by-elections, said at the National Endowment for Democracy event in Washington that it was premature to lift sanctions.

“If you look at it right now, even in the different ethnic areas all the companies are run by the government. Therefore if you open the road to people coming and doing business, the ethnic people will have to suffer more than before,” she said.

Appearing at the same event, Zarganar — Burma’s most famous comedian who was freed in the recent amnesty — said that he did not want to take a stance on the controversial issue of lifting sanctions.

But he said: “[Due to] the sanctions from American or from Europe, our government changed their mindset. I don’t like sanctions, but according to the strategic thinking, it’s a very good instrument.”