Legislators and political advisors have urged Washington to condemn Saturday's deadly attack in southwest China as terrorist activity after the U.S. downplayed its severity.

"The U.S. definition of terrorist activities hinges on its own political interests," Yin Zhuo, director of the Expert Consultation Committee of the People's Liberation Army (PLA) Navy, told Xinhua on Monday.

"It should discard its entrenched double standard on terrorism," added Yin, who is also a member of the National Committee of the Chinese People's Political Consultative Conference (CPPCC), China's top political advisory body.

His remarks came after the U.S. Embassy in China called the attack at a Kunming train station that left 29 dead and over 140 others injured a "horrible and totally meaningless act of violence" on its official Sina Weibo account, short of labelling it a terrorist attack.

The wording promoted a slew of criticism from Chinese netizens on the country's social networking sites.

China said that evidence at the scene of the slaughter pointed to separatists from northwestern China's Xinjiang Uygur Autonomous Region, which has been haunted by suicide bombings and deadly assaults.

"There is a sharp difference between a 'terrorist attack' and an 'act of violence,'" Yin told Xinhua.

He said that the U.S. refused to admit the existence of any terrorists in Xinjiang except for the East Turkistan Islamic Movement separatists.

"Only in that way can the other terrorists who intend to split China get financial aid," he said.

CPPCC National Committee member Liu Jian said that the ambiguous U.S. stance on the terrorist activities in Xinjiang will do harm to China without benefiting the U.S.

"According to the logic of the country (U.S.), only those who are harming its own interests are real terrorists," added Liu, the former vice president of the Equipment College of the Chinese People's Liberation Army.

Muhanmetemin Yasin, a member of China's National People's Congress (NPC) Standing Committee, said that the U.S. stance on the latest Kunming attack is a continuation of its chronic attitude toward the terrorist activities in Xinjiang.

The Xinjiang lawmaker also urged the U.S. to drop its double standard on terrorism.

On Monday, at the opening of the annual session of the CPPCC National Committee, Chinese leaders and political advisors paid silent tribute to the victims of the terrorist attack in Kunming.

The annual session of the NPC, the top legislature, is scheduled to open on Wednesday.