BEIJING (Reuters) - European Union ambassadors in Beijing will not be visiting China’s western region of Xinjiang this week after receiving a government invitation, as such a trip needs “careful preparation”, a spokesperson for the bloc said on Monday.

China has been stepping up a push to counter growing criticism in the West and among rights groups about a controversial de-radicalization program in heavily Muslim Xinjiang, which borders Central Asia.

Critics say China is operating internment camps for Uighurs and other Muslim peoples who live in Xinjiang, though the government calls them vocational training centers and says it has a genuine need to prevent extremist thinking and violence.

China’s foreign ministry said late last week it would invite Beijing-based European diplomats to visit soon. Sources had told Reuters the invitation was made to EU ambassadors based in Beijing.

A spokesperson for the EU Delegation to China said they, along with embassies of member states in Beijing, on March 21 received a formal invite from China’s foreign ministry to send ambassadors to Xinjiang from March 27-29.

“While the EU and EU Member States in principle welcome the invitation, such a visit requires careful preparation in order to be meaningful,” the spokesperson said.

“Discussions to this end are ongoing, hence the proposed trip will not take place this week. The EU remains open to a future visit taking into account our expectations.”

Speaking earlier on Monday, Chinese Foreign Ministry spokesman Geng Shuang said talks were ongoing about the trip. He did not elaborate.

A U.S. official told Reuters that “highly choreographed” tours to Xinjiang organized by the Chinese government were misleading and propagated false narratives about the troubled region.

Geng said trips organized by China’s government to Xinjiang for diplomats and reporters have been very successful at showing people the true situation there, and denounced U.S. criticism as “slander”.

Speaking at a daily news briefing, Geng said such trips were to raise the international community’s understanding about Xinjiang’s social and economic development.

“The people who have been on the trips felt for themselves the real situation Xinjiang’s calm and order and the happy lives and jobs of all the people’s there, and all positively appraised China’s policy governing Xinjiang,” Geng said.

The U.S. criticism “does not accord with the facts”, he added. “It is purely rumor starting and slander.”

China resolutely opposes the United States interfering in its internal affairs using the Xinjiang issue, Geng said.

“At present Xinjiang is politically stable, the economy is developing and society is harmonious.”

There have been two visits by groups including European diplomats to Xinjiang this year. One was a small group of EU diplomats, and the other by a group of diplomats from a broader mix of countries, including missions from Greece, Hungary and North African and Southeast Asian states.

A Reuters journalist visited on a government-organized trip in January.

Late last year, more than a dozen ambassadors from Western countries, including France, Britain, Germany and the EU’s top envoy in Beijing, wrote to the government to seek a meeting with Xinjiang’s top official, Communist Party chief Chen Quanguo, to discuss their concerns about the rights situation.

Two sources familiar with the situation told Reuters that China was not offering a meeting with Chen to the EU ambassadors.

The administration of U.S. President Donald Trump has weighed sanctions against senior Chinese officials in Xinjiang, including Chen.