BEIJING, May 15 (Reuters) - Beijing on Friday ordered Chinese entities not to assist a European Union anti-subsidy investigation into the Chinese security firm Nuctech.

The justice ministry said the EU was arbitrarily demanding "extensive and non-essential information within China from Chinese entities", which it termed "unjustified extraterritorial jurisdiction."

The order is the first application of regulations introduced in April to protect Chinese firms against what Beijing deems improper foreign interference as it expands its economic toolkit. 

"We urge the EU to immediately correct wrong practices and create a fair, just and predictable market environment for China-EU cooperation," a justice ministry spokesperson said in a separate statement, threatening "firm countermeasures".

Echoing a statement by China's Ministry of Justice, the Ministry of Commerce said on Saturday that China firmly opposes the EU's use of the Foreign Subsidies Regulation against Chinese companies, saying the bloc has broadened its investigations and sought extensive information from within China that is unrelated to the probes.

The EU opened an in-depth investigation into Nuctech in December over concerns that it may have received subsidies that could boost its competitiveness in Europe.

The requests for information are "standard measures", a European Commission spokesperson said in an email.

"The Foreign Subsidies Regulation does not distinguish between companies based on their nationality or ownership and is consistent with the EU's international obligations," he said.

The company makes body and luggage scanners for airports and ports in more than 170 countries, and was among Chinese tech firms blacklisted by the U.S. government in 2020 over security concerns.

(Reporting by Che Pan, Shi Bu, Xiuhao Chen, Liz Lee and Inti Landauro, Editing by Louise Heavens)