U.S. Deputy Secretary of State Stephen Biegun reportedly conveyed the U.S. government's concerns about a South Korean bill prohibiting the sending of anti-North Korea leaflets across the border during his recent visit to Seoul.

Citing unidentified sources, the Washington Post said on Thursday that Biegun had "privately conveyed" the U.S. government's concerns during a recent trip to Seoul. 

Josh Rogin, a columnist for the U.S. newspaper, made the claim in the article titled "South Korea's new anti-leaflet law sparks backlash in Washington."

Rogin said Biegun had conveyed the U.S. government's concern before the South Korean parliament passed the controversial bill, adding the Trump administration has kept silent on the issue. 

Biegun visited South Korea last week and the South Korean parliament passed the bill earlier this week. 

Rogin said the passage is causing backlash in Washington, where lawmakers and nongovernmental organizations are worried that Seoul is sacrificing free speech and human rights to appease North Korean leader Kim Jong-un.