A new video shows a black man confronting a Starbucks worker after he was apparently not allowed to use the bathroom while a white man was allowed access. The video was shared on Twitter by an activist on Monday.

Last week, in a separate incident, two black men were arrested after asking to use a Starbucks bathroom without ordering.

Starbucks has apologized and said that managers will undergo "unconscious bias" training.

Starbucks is under fire for its treatment of African-American men.

Kevin Johnson, Starbucks' CEO, was forced to apologize this weekend after a video of two black men being arrested at a Philadelphia location of the coffee chain went viral. Employees called the police after the men refused to leave the Starbucks after asking to use the restroom without having purchased any drinks.

On Monday, a new video emerged of a black man confronting a Starbucks worker after he was apparently not allowed to use the bathroom while a white man was allowed access.

In the video, posted to Twitter by writer and activist Shaun King, Starbucks employees appear to allow a white man to use a Los Angeles area store's bathroom without having purchased any food or beverage.

The black man recording the video, identified by King as Brandon Ward, questions employees why the white man was allowed to use the bathroom without making purchases when he was not.

"I just tried to use the bathroom like you did, and they gave it to you," Ward asks in the video, as agitated Starbucks workers tell him he needs to leave. "Is it because of my skin color?"

Ward told KTLA that the incident happened January 23, but he posted the video to Facebook Saturday.

"Please know that we take this video and the commentary around it very seriously, and are working closely with the team to learn from our mistakes," a Starbucks representative said in an email to Business Insider. "As you may have read in the letter from our CEO, we are fully investigating our store practices and guidelines across the company."

Watch the video below:

'It serves the needs of only some'

According to some experts, questions of who is welcome at Starbucks and who is excluded are an ongoing problem for the brand.

"While it appears to offer equal access, in reality, it serves the needs of only some," Temple University professor Bryant Simon writes in his book "Everything but the Coffee: Learning about America from Starbucks."

Simon visited more than 400 Starbucks locations while researching the book, which was published in 2009. As he spent hundreds of hours in Starbucks, he realized different customers received different treatment, with the bathroom policy acting as a key example.

Simon writes:

"To use the bolted bathrooms, you had to ask for a key. This seemed to be no problem for people wearing suits and expensive ski jackets or white college professors like myself. We ask for the key, no questions asked. But for the homeless and for people of color, especially unattached men, things aren't so simple and easy. Several times I have seen African-American men go up to the counter for the key. Giving the man the once-over the manager or the shift supervisors hesitates and says, 'Have you bought anything? The bathrooms, you know, are for customers only.'"

Starbucks said that it is working to make institutional changes to address these problems in the long term, with plans to instruct workers to better understand when police assistance is necessary and have managers undergo "unconscious bias" training. Starbucks is holding a company-wide meeting this week to "share our learnings, discuss some immediate next steps and underscore our long-standing commitment to treating one another with respect and dignity."