The United States has expressed its "strong support" for the two Koreas' plan to study the possibility of reconnecting a railway across their border.

Lee Do-hoon, special representative for Korean Peninsula peace and security affairs, relayed the U.S. position to reporters after meeting with his American counterpart, Stephen Biegun, earlier on Tuesday in Washington.

Lee was referencing reports that the U.S. is reluctant to see the study move forward due to concerns reconnecting the railways could dampen sanctions on Pyongyang.

The Koreas had agreed to launch the study late last month to enable a groundbreaking ceremony by early December but that schedule was delayed amid continued consultations between Seoul and Washington. 

Lee said Seoul still aims to hold the ceremony before the end of the year.