A Japanese American woman who was attending a conference last week at the Sheraton Philadelphia Downtown Hotel was horrified to find the slur Jap written on her bill, according to the Japanese American Citizens League and news sources.

About 350 workers at the hotel, at 17th and Race Streets, will undergo sensitivity training as a result.

The league's Philadelphia chapter, part of the nation's oldest and largest Asian civil rights group, will participate in the training to inform the hotel staff  "about the history of anti-Asian racism, why 'Jap' is not an acceptable term even when used to abbreviate Japan, and how to be better accommodating to Asian American and Pacific Islander guests," the group said on its Facebook page.

"It was kind of like a punch in the stomach," the woman, Eileen Yamada Lamphere, told NBC10.

Lamphere, among the guests who attended the national conference of the Japanese American Citizens League, said that for Japanese people, the slur is as bad as the worst pejorative used against African Americans.

The Philly Voice website reported that, according to the hotel, the word was used as shorthand by an employee who did not realize it was a racial slur.

For many Japanese, the term evokes the anti-Japanese racism of World War II.

"We are continuing to investigate this matter and deeply regret that one of our guests experienced this issue," a Sheraton Hotel spokesperson said, according to WHYY. "Based on the results of our investigation we will take the appropriate actions, including refreshing our sensitivity/diversity/inclusion training, to ensure this doesn't happen again."

Philadelphia was the scene of a national furor earlier this year when a manager at a Center City Starbucks called police on two African American men who were sitting in the store, waiting for an acquaintance to arrive. Starbucks instituted companywide racial-bias training as a result.