U.N.'s Ban "gravely concerned" for Myanmar's Suu Kyi

United Nations Secretary-General Ban Ki-Moon speaks at the United Nations headquarters in New York May 4, 2009.

UNITED NATIONS (Reuters) - U.N. Secretary-General Ban Ki-moon expressed "grave concern" on Thursday over reports that Myanmar opposition leader Aung San Suu Kyi was charged with violating her house arrest and could face new jail time.

"The Secretary-General is gravely concerned about the news that Daw Aung San Suu Kyi has been moved to the Insein Prison to face criminal charges," U.N. spokeswoman Marie Okabe told reporters.

She said Ban believes Suu Kyi "is an essential partner for dialogue in Myanmar's national reconciliation and calls on the government not to take any further action that could undermine this important process."

Ban is convinced that Suu Kyi and all others in the country formerly known as Burma "who have a contribution to make to the future of their country" should be free to do so, Okabe said.

Suu Kyi's opposition National League for Democracy (NLD) said she faces up to five years in jail after an American intruder sneaked into her lakeside home.

Opposition activists denounced her trial, set to begin on Monday, as a ploy by the country's junta to keep Suu Kyi, 63, sidelined ahead of elections in 2010.

The NLD, which won a landslide election victory in 1990 only to be denied power by the military, "strongly condemned" the new charges two weeks before her latest six-year detention is due to expire on May 27.

The Nobel Peace laureate has spent 13 of the past 19 years in detention, most of it held virtually incommunicado at her home, her telephone line cut, mail intercepted and visitors restricted.

(Reporting by Louis Charbonneau; Editing by Simon Gardner)