The U.S. government drew a clear line Monday between a sex scandal roiling South Korea and Seoul-Washington relations.

Police in Washington, D.C., apparently at the instruction of federal prosecutors, are looking into allegations that then-presidential spokesman Yoon Chang-jung sexually abused a Korean-American woman during his stay here last week as part of the entourage accompanying President Park Geun-hye.

The scandal has already dealt a heavy blow to the image of the Park administration, although Yoon publicly denied the allegations that he "grabbed the buttocks" of an intern in her early 20s dealing with duties related with Park's visit.

Yoon immediately sneaked out of the U.S. and returned to Seoul.

Park's office, Cheong Wa Dae, dismissed him from his post while she was on a trip to the U.S., mainly for summit talks with President Barack Obama.

The Park-Obama summit last Tuesday was widely said as a huge success but it was overshadowed by the sex scandal, which led to a formal apology by the South Korean president.

Many Koreans are worried that it may have a further impact on South Korea-U.S. relations.

A State Department spokeswoman dismissed that concern Monday.

"No, I would not connect the two," Jennifer Psaki said at a press briefing, asked about the possibility that the scandal will affect the two countries' ties. "We have an ongoing working relationship with South Korea on a number of issues."

She refused to go into details about any consultations with Seoul on the Yoon case.

"I would refer you to the government of South Korea," she said, wrapping up her first press briefing as the department's spokeswoman.

Local police remained guarded about their probe.

"The Metropolitan Police is aware of a misdemeanor sexual abuse allegation. Considering this case is still pending investigation, we can not make any further comments," Officer Tisha Gant at the Office of Communications told Yonhap News Agency by phone.

She and other officials rejected repeated interview requests by Yonhap.

Criticism has been growing over Yoon's denial of the charge but also over the handling of the incident by Cheong Wa Dae and South Korean officials in Washington. There are suspicions that the presidential office nudged Yoon to leave Washington to avoid immediate police interrogation.

The South Korean government has denied claims and it has asked U.S. law-enforcement authorities to speed up a related probe.

"We delivered an intent to cooperate with the investigation by the U.S. authorities," South Korean Ambassador to the U.S. Choi Young-jin told reporters. "We also conveyed hope that (relevant) legal procedures proceed fast."

Meanwhile, an informed source said that federal prosecutors are spearheading the Yoon case.

Those who work at a Washington hotel wine bar, where Yoon is alleged to have sexually abused the intern, refused to talk about what they saw. (Yonhap News)