North Korean authorities said on Monday that the two US citizens had provided testimony which confirmed the evidence against them.

"The relevant organ of the (North) is carrying on the investigation into them and making preparations for bringing them to court on the basis of already confirmed charges," said the state-run KCNA news agency.

Matthew Todd Miller, 24, was detained in April after he ripped up his tourist visa upon arriving in North Korea, requesting asylum in the communist nation.

North Korean authorities also arrested 54-year-old Jeffrey Edward Fowle in April after he reportedly left a bible in his hotel room. Fowle's family denies that he was on a mission trip for his church.

Last year, Korean-American Kenneth Bae was arrested and sentenced to 15 years of hard labor on charges of trying to topple the regime. A North Korean court described Bae as a militant Christian evangelist.

The US State Department issued a travel warning in May, urging Americans to avoid travel to North Korea due to "the risk of arbitrary detention and arrest."

slk/av (AP, AFP, Reuters)