The National Security Agency created “back doors” into networks maintained by the Chinese telecommunications company Huawei, according to a report released on Saturday.

The report comes from a document provided by the former NSA contractor Edward Snowden and disclosed by the New York Times and Der Spiegel. It will add to embarrassment in US government circles, in light of an October 2012 US House of Representatives intelligence committee report which said US firms should avoid doing business with Huawei and another Chinese telecoms company, ZTE, because they posed a national security threat.

President Barack Obama is scheduled to meet Chinese president Xi Jinping in the Hague on Monday, during a six-day trip to Europe in which he will attempt to strengthen international opinion against Russia's occupation of Crimea. The first lady, Michelle Obama, is currently in China with her mother and two daughters; on Saturday she told an audience of students at Peking University's Stanford Centre that web access should be “a universal right”.

On Saturday, William Plummer, Huawei's vice-president of external affairs, said in an email to the Associated Press: "Huawei has declared its willingness to work with governments, industry stakeholders and customers in an open and transparent manner, to jointly address the global challenges of network security and data integrity.

“The information presented in Der Spiegel and the New York Times article reaffirms the need for all companies to be vigilant at all times."

At the time of the 2012 House report's release, intelligence committee chairman Mike Rogers said in comments broadcast on the CBS programme 60 Minutes: “Find another vendor [than Huawei] if you care about your intellectual property; if you care about your consumers' privacy and you care about the national security of the United States of America.”

In July 2013 Huawei rebutted such claims – the former CIA director General Michael Hayden also said he believed the company supplied information to the Chinese government – calling them “racist”. The same month, the UK government opened a review of the firm. In October 2013, the company's deputy chairman, Ken Hu, denied ever having been told to spy on customers.

The Times and Spiegel reports said that in an operation code-named Shotgiant, the NSA gained access to the company's servers in Shenzhen, obtaining information and monitoring communications between executives. Among those whose emails the NSA was able to read was the president of Huawei, Ren Zhengfei.

Huawei, which maintains operations in the UK despite all but ending its attempts to access the US market, due to government resistance, claims to connect a third of the world's population. It is also the world's third-largest maker of smartphones, after Apple and Samsung.

Saturday's reports quoted from the 2010 document: “Many of our targets communicate over Huawei-produced products. We want to make sure that we know how to exploit these products.”

In response to previous stories derived from documents obtained by Snowden and leaked to media outlets including the Guardian last year, the US government has repeatedly said the NSA breaks into foreign networks only for reasons of national security.

On Saturday an NSA spokeswoman, Caitlin Hayden, told the Times: “We do not give intelligence we collect to US companies to enhance their international competitiveness or increase their bottom line. Many countries cannot say the same.”

The Times quoted Plummer as saying: “The irony is that exactly what they are doing to us is what they have always charged that the Chinese are doing through us.”

Security against cyber warfare carried out by China is an increasing concern to the US. In February 2013 a US security company said it had pinpointed the existence of a unit within the People's Liberation Army responsible for a number of cyber attacks against the US.

The Times also quoted James A Lewis, a cyber security expert at the Centre for Strategic and International Studies, who said: “China does more in terms of cyberespionage than all other countries put together.”