U.S. Secretary of State Rex Tillerson appears to have toned down his unexpectedly stern words on China's actions in the disputed South China Sea made during his confirmation hearings, an apparently leaked document has shown.

The document, a series of written responses to questions by Maryland Sen. Ben Cardin during Tillerson's confirmation hearing last month before the Senate Foreign Relations Committee, was posted to the websites of environmental advocacy groups earlier this month.

The document is authentic, a Foreign Relations Committee spokesman confirmed to The Japan Times on Tuesday.