San Francisco  - Friends, family and colleagues of the two US journalists held in North Korea held a vigil and called for their release Wednesday, 99 days after they were captured.

Korean-American Euna Lee, 32, and Chinese-American Laura Ling, 36, were sentenced in early June by North Korea's central court to 12 years of hard labour for committing a "grave crime" against North Korea and illegally entering the country.

They were arrested at the Chinese-North Korean border on March 17 while on assignment for Current TV, and are believed to have mistakenly crossed the border, but details of their arrest by North Korean border guards remained unclear.

"They have confessed and apologized," said Iain Clayton, Laura Ling's husband. "We are asking the government of North Korea to show compassion and to release the girls to their families." (dpa)