The United States says it is increasingly concerned about North Korea’s plan to put two American journalists on trial.

State Department Spokesman Ian Kelly told reporters Thursday that Washington is stepping up various diplomatic efforts for the welfare and release of the two journalists. Kelly said Washington is currently seeking further information through its protecting power, the Swedish Embassy in Pyongyang, on reports that the two journalists will be put on trial June fourth.

Asked if the U.S. is considering sending a high-ranking envoy to North Korea to help facilitate their release, Kelly said that there are no plans to do so at this time.

The two women, Euna Lee and Laura Ling of San Francisco-based Current TV, have been detained for nearly two months after being taken into custody by North Korea on March 17th near the Chinese-North Korean border while filming a documentary on North Korean escapees.