In his last act, former U.S. Secretary of State Mike Pompeo announced on Tuesday that the U.S. determined that China had committed so-called "genocide and crimes against humanity" by repressing Uygur Muslims in northwest China's Xinjiang Uygur Autonomous Region. Officials in Xinjiang vehemently protested the accusations late Wednesday during a press briefing in the region's capital city Urumqi.

Xu Guixiang, deputy head at the Publicity Department of the Communist Party of China Xinjiang Uygur Autonomous Regional Committee, called Pompeo's determinations "a pack of lies."

"The so-called determination is just a piece of scrap paper," said Xu, adding it grossly interferes in China's internal affairs and tramples on international law and norms governing international relations.

"Xinjiang and its people of all ethnic groups strongly denounce and oppose it," Xu said.

According to statistics from the press briefing, the population of ethnic minorities including the Uygur minority had grown consistently from 2010 to 2018. The Uygur population grew by more than two million to 12.7 million in the region, at a growth rate of more than 25 percent. The overall population in Xinjiang grew from 21.81 million to 24.86 million, at a growth rate of close to 14 percent.

"Uygur population is growing faster than that of the general population in Xinjiang, also faster than that of the population of other ethnic minorities, and is significantly faster than that of the Han Chinese population," said Elijan Anayit, spokesperson of the information office of Xinjiang's regional government, adding the figures show how Pompeo's determination was grossly wrong.

"Is there any place around the world where there are increases on population after so-called genocide? Pompeo must have rocks in his head," the spokesperson said.

It's not the first rebuke leveled at the U.S. politician.

Chinese Foreign Ministry spokesperson Hua Chunying also called Pompeo "a doomsday clown" when questioned about the latter's declaration of so-called genocide, at a regular press briefing on Wednesday.

The foreign ministry also announced on Thursday sanctions that bar Pompeo and others of the Trump administration from entering or doing business with China.