US President Barack Obama has said he is "deeply concerned" by North Korea's reported sentencing of two US journalists to 12 years' hard labour.
The US was working through all channels to secure their release, a spokesman for Mr Obama said.
The journalists, Euna Lee and Laura Ling, were found guilty of "hostile acts" and illegal entry into North Korea, state media reported.
They were arrested in March after allegedly entering from China.
Their trial was held amid growing tensions over North Korea's nuclear programme and recent missile tests.
"We are engaged through all possible channels" to secure the journalists' release, White House spokesman Bill Burton said in a statement on Monday.
The trial began on Thursday, and on Monday North Korea's state media agency, KCNA, released a report saying the two had been convicted.
"The trial confirmed the grave crime they committed against the Korean nation and their illegal border crossing... and sentenced each of them to 12 years of reform through labour," the brief report said.
The news agency gave no further details.
Outside observers were not allowed to witness the hearing at Pyongyang's court.
The verdict means that the journalists face the prospect of spending years in one of the North's prison camps, where conditions are reported to be extremely harsh, the BBC's Chris Hogg in Seoul says.
Euna Lee, a Korean-American, and Laura Ling, a Chinese-American, were arrested by North Korean guards on 17 March while working on the China-North Korea border on a story about refugees for California-based internet broadcaster Current TV.
Some reports have suggested the women were held while on Chinese soil, but Pyongyang's state media say they had illegally entered North Korea.
The pair have been held in detention since their arrest.
US Secretary of State Hillary Clinton earlier described the charges against the two women as "baseless". She is thought to be considering sending an envoy to try to negotiate their release.
There has been speculation that former US Vice-President Al Gore might travel to Pyongyang. He is the co-founder of Current TV.
There are fears Ms Lee and Ms Ling will now be used as "bargaining chips" by North Korean leader Kim Jong-il in his efforts to win concessions from Washington, our Seoul correspondent says. These concessions could include humanitarian aid or direct talks with Washington, analysts say.
The US has so far said negotiations can only be held under the currently-stalled six-party talks on nuclear disarmament, which also includes South Korea, China, Japan and Russia.
The women's families have appealed for clemency and asked Pyongyang and Washington not to link their case with the current diplomatic stand-off.
Tensions have increased in the region since North Korea conducted a nuclear test in May and then test-fired several missiles. Another long-range missile test is believed to be planned for later this month.
The UN Security Council is discussing tightening sanctions against Pyongyang, and Mrs Clinton said on Sunday that the US was considering reinstating North Korea in its list of state sponsors of terrorism.