The U.S. State Department issued a new warning against traveling to North Korea on Thursday, saying the communist regime threatens to treat detained American citizens according to its "wartime law."

Pyongyang made the threat after the U.S. imposed sanctions on North Korean leader Kim Jong-un for his roles in the country's human rights abuses. U.S. officials say the North has also been refusing to grant consulate access to two American citizens detained in the country.

"The State Department strongly urges U.S. citizens to avoid all travel to North Korea/the Democratic People's Republic of Korea due to the serious risk of arrest and long-term detention under North Korea's system of law enforcement," the department said in the latest travel warning.

The latest warning came about three months after the last warning.

The North "imposes unduly harsh sentences, including for actions that in the United States would not be considered crimes" and threatens to treat U.S. citizen detainees "in accordance with 'wartime law of the DPRK,'" the department said.

"At least 14 U.S. citizens have been detained in North Korea in the past ten years. North Korean authorities have detained those who traveled independently and those who were part of organized tours," the department said.

It also warned that foreign visitors could end up behind bars for what would not be considered unlawful actions in the rest of the world, such as possessing material critical of the North, proselytizing or carrying out religious activities, and having unauthorized interaction with the local population.

The North "routinely delays or denies consular access" to American detainees, even though it is required to allow consular visits by the Swedish Embassy within two days after a request is made under a consular agreement between the two countries, the department said.

The Swedish Embassy serves as the protecting power for the U.S. in the North as Washington and Pyongyang have no diplomatic relations.

Two American citizens -- college student Otto Warmbier and Korean-American pastor Kim Dong-chul -- are currently detained in the North after being sentenced to long prison terms for what Pyongyang calls subversive acts against the country.

American citizens have often been detained in North Korea on charges of anti-state and other unspecified crimes. Widespread views have been that Pyongyang has often used the detentions as bargaining chips in its negotiations with Washington. (Yonhap)