BEIJING (AFP) - Visiting US First Lady Michelle Obama, along with her daughters and mother, came face-to-face with China's Terracotta Warriors on Monday on a week-long tour which has taken in several major sites while skirting politics.

The family stepped into one of the vast pits at the site outside Xian, in the northern province of Shaanxi, to view the ancient statues while a guide showed them around.

The site houses 8,000 lifesize warriors left by China's first emperor Qin Shi Huang who reigned in the 3rd century BC, a hugely popular tourist attraction that saw five million visitors last year.

Since arriving in Beijing on Thursday night for a visit focusing on "soft" issues, Mrs Obama has toured the Forbidden City, a former imperial palace, with her Chinese counterpart Peng Liyuan, and promoted education and study abroad.

She touched briefly on politics during a speech on Saturday at Peking University's Stanford Centre that was otherwise devoted to encouraging American students to study in China.

"When it comes to expressing yourself freely, and worshipping as you choose, and having open access to information - we believe those are universal rights that are the birthright of every person on this planet," she said.

"We believe that all people deserve the opportunity to fulfil their highest potential, as I was able to do in the United States."

As her motorcade arrived at the US embassy in Beijing on Sunday for a roundtable with Chinese educators and families, two people outside the premises began shouting.

Police and men in grey sweatshirts hurried to subdue them, and it was unclear why they were yelling.

Later that day, she strolled along the Great Wall north of the capital.

Vendors at the tourist site appeared to have removed T-shirts that are typically on sale showing President Obama in a Mao hat, with one merchant revealing a boxful of the souvenirs stored in the back of her tent.