An American man has been detained by North Korean authorities.

Two State Department officials told CNN on Tuesday that the State Department is working with the Swedish Embassy in Pyongang.

The report said officials of the Swedish Embassy have been granted consular access to the man and have visited him. The Swedes have also asked North Korean authorities for regular visits.

Sweden represents Washington’s interests in the North because the United States and North Korea do not have diplomatic relations.

U.S. State Department spokesman Mark Toner said that it would call on North Korea to release the American on humanitarian grounds. However, as the news comes just weeks before former U.S. President Jimmy Carter travels to Pyongyang, Toner was not sure whether the State Department will ask Carter to negotiate a release for the detained citizen.

The report said that in recent years, North Korea has detained several Americans, including a Christian activist and two journalists, increasing tension levels in what is already a rocky relationship between Pyongyang and Washington.