Cosmetics chain Sephora closed its US stores for an hour on Wednesday to hold an "inclusivity workshop" for its employees, a month after a Grammy-nominated black singer said she was racially profiled in the shop.

Sephora's downtown Washington store opened an hour later than usual.

"We truly belong to something beautiful," said a sign on the door, a reference to the company's recent "We Belong to Something Beautiful" advertising campaign.

"Thank you for your understanding," it said.

Sephora said the workshops would involve the 16,000 employees of its stores, distribution centers, call centers and US corporate headquarters.

The diversity training comes a month after the African-American singer SZA said she was subjected to racial profiling at a Sephora in Calabasas, California.

She tweeted that someone at the beauty chain's store had "called security to make sure I wasn't stealing."

SZA has been nominated for several Grammy awards, including this year for best new artist and best R&B song.

Sephora said the workshop and ad campaign were planned prior to SZA's experience.

"However, it does reinforce why belonging is now more important than ever," the company said in a statement.

"Sephora is a client-centric company and creating a welcoming space for all our clients is our top priority," it said.

"The 'We Belong to Something Beautiful' campaign has been in the works for a year, and the plan to close... for a one-hour inclusivity workshop with our 16,000 employees has been in development for over six months.

"This store closure is part of a long journey in our aspiration to create a more inclusive beauty community and workplace," the company said.

"We'll be discussing what it means to belong, across many different lenses that include, but are not limited to, gender identity, race and ethnicity, age, abilities, and more."

Sephora is owned by Paris-based luxury giant LVMH, whose 70 brands range from Louis Vuitton, Hennessy and Givenchy to Celine, Dior and Guerlain.