BERLIN, March 12 (Xinhua) -- Following a warning letter by the U.S. ambassador in Berlin, German Chancellor Angela Merkel said on Tuesday that it "goes without saying" that the German government would define its own security standards in its 5G expansion.

Merkel added that security in the expansion of Germany's 5G mobile network was a "precious asset" for the German government, and security standards would be discussed with Germany's partners in Europe and the United States.

U.S. ambassador to Germany, Richard Grenell, had reportedly warned that intelligence cooperation between the United States and Germany could continue at its current level only if Chinese firms were excluded from the construction of Germany's 5G network, according to a letter sent to German economy minister Peter Altmaier.

Other German politicians were also critical of Grenell's letter.

"This federal government does not need any prompting or information from the American ambassador to take steps that make sense from a security policy point of view," said Michael Grosse-Broemer, the parliamentary director of the governing conservative union (CDU/CSU) in the Bundestag.

Vincent Pang, head of Western Europe with China's telecoms firm Huawei, told the German newspaper Handelsblatt that "a country should not use its political power to harm a commercial enterprise. The U.S. is going too far."

Germany is currently considering tightening the security rules for its telecoms infrastructure and Huawei's involvement in the construction of Germany's 5G network.

Bidding for the licenses for the expansion of Germany's new 5G network is expected to start on March 19.