BEIJING — A Chinese billionaire venture capitalist who has strongly advocated more liberal political and social policies was detained Friday by Beijing police officers, friends of the businessman said.

The businessman, Wang Gongquan, 51, is a close friend of Xu Zhiyong, a lawyer who was formally arrested last month on a charge of “assembling a crowd to disrupt order in a public place.” Mr. Wang was detained on the same charge, according to a photograph of the warrant that circulated online on Friday. One human rights group said Mr. Wang was in Beijing No. 3 Detention Center, where more than a dozen others with ties to the New Citizens’ Movement, led by Mr. Xu, are being held.

Mr. Wang was taken from his home by more than 20 police officers around 11:30 a.m., said Chen Min, another well-known rights advocate, who goes by the pen name Xiao Shu. The police searched the home for more than two hours and took away a computer, two framed pictures and small “citizen pins” that Mr. Wang presumably had made at some point, Mr. Chen said.

The pins might have been collected by the police as potential evidence in a case against Mr. Wang. They appear to be similar to “citizen stamps” that Mr. Wang ordered made years ago. Caixin, an investigative business magazine, reported in 2011 that Mr. Wang had commissioned 100 of the stamps, which were the same size as a one renminbi coin and bore the engraved images of the Chinese flag, an open book with the title “Constitution,” and the phrase “Chinese Citizen.”