SEOUL: Two American journalists accused of entering North Korea illegally and engaging in "hostile acts" faced the country's highest court Thursday for a trial on charges that could land them up to 10 years in a labor camp.

Laura Ling and Euna Lee, reporters for former Vice President Al Gore's California-based Current TV media venture, were arrested March 17 near the North Korean border while on a reporting trip to China.

The trial at Pyongyang's Central Court was to begin at 3 p.m. (0600 GMT), the official Korean Central News Agency said in a brief dispatch. No further details were available.

The proceedings come at a time of mounting tensions on the Korean peninsula, with the communist regime launching a long-range rocket in April and conducting an underground nuclear test last week in defiance of international demands for restraint.

Even as ambassadors to the U.N. Security Council discussed how to punish the nation for the bold atomic test, there were indications that the North was preparing to test-fire a long-range missile from a west coast site, one capable of striking the U.S., officials said.

There were fears the women, jailed separately in the North Korean capital, may become pawns in political negotiations between Pyongyang and Washington. Their families pleaded for clemency and urged the governments not to let politics decide their fate.

The Korean War foes do not have diplomatic relations, and analysts called North Korea's recent belligerence a bid to grab President Barack Obama's attention and to speed up any direct negotiations.

"One explanation of North Korea's behaviour is that Pyongyang is trying to catch Washington's attention. It believes the Obama administration has not made North Korea a priority," said David Straub of Stanford University's Korean studies programme.

State-run media have not defined the exact charges against them, but South Korean legal experts said conviction for "hostility" or espionage could mean five to 10 years in one of North Korea's notoriously harsh labour camps and that a ruling by the top court would be final.

The circumstances of their arrest remained unclear. The Current TV team had gone to the Chinese border city of Yanji to report on North Korean women and children who had crossed the border from northeast North Korea.

"Too many sad stories," Ling posted to Twitter days before her arrest.

They were arrested March 17 somewhere near the frozen Tumen River dividing North Korea and China while two others, a cameraman and their local guide, managed to evade the North Korean guards.

The reporters' families say the women had no intention of crossing into North Korea. They spoke to them by phone once, last week.

"If at any point they did, we are truly sorry and we know the girls are too," Ling's sister, TV journalist Lisa Ling, said in a statement read aloud at vigil nationwide Wednesday night, adding that she wished it were "all a bad dream." "What they set out to do almost three months ago was to tell the world a story," she said. "I know that what Laura and Euna were trying to do was give people a voice." "In doing so, their voices were silenced," she said. "They have been crying out loud in isolation, but their cries of anguish have gone unheard." In New York, dozens turned out in a drenching rain for a vigil led by Ling's cousin Angie Wang. Some held yellow chrysanthemums.

"Nobody should be holding people for purely political gamesmanship purposes," said J.B. Miller, 44.

At a San Francisco vigil, supporters held signs reading: "Free Euna Lee and Laura Ling" and "Liberate Laura and Euna Now." In Washington, State Department spokesman P. J. Crowley called for their release. "We continue to consult with the families. And there is no higher priority that we have than protection of American civilians abroad. And we, again, hope that North Korea will forego this legal process and return them to the United States," he said Wednesday.

Media groups also pressed for their release.

"We urge that their fate not be linked to the ongoing security situation on the Korean Peninsula," Bob Dietz of the Committee to Protect Journalists said in a statement. "Euna Lee and Laura Ling were acting as journalists, not criminals, and should be released." Roxana Saberi, an American journalist who spent four months in an Iranian prison before being released May 11 on a suspended sentence for spying, urged the women to "remain strong." "I haven't been to North Korea, but I understand it is even more of a closed state than the Islamic Republic of Iran," Saberi said in a statement.

"Still, if Laura and Euna's situation resembles anything like mine, I can imagine a little of what they might be wishing for: The presumption of innocence until proven guilty. A fair trial, with access to attorneys of their choice and the right to study what is claimed as evidence against them. More contact with their families, whom they probably worry are worrying about themselves!"