Chinese PC maker Lenovo told the Global Times that the company has been paying close attention to bans by intelligence agencies, after safety concerns led to Lenovo products being forbidden from networks in five countries.

"We have not received official bans from those countries yet. We learned about this online via foreign media outlets just days ago," Zhao Zhipan, spokesperson of Lenovo, told the Global Times, adding that it is currently inconvenient for the company to comment.

The bans were revealed by the Australia-based Financial Review on Saturday. They allege that the "secret" and ''top secret" networks of the intelligence and defense services of Australia, the US, the UK, Canada and New Zealand have forbidden Lenovo computers to be used as they are easy to be hacked due to the existence of a hardware "backdoor."

The report also implies that similar safety problems were found after a series of lab tests in 2005, when Lenovo successfully acquired IBM's personal computer business. The tests suggested that Lenovo technology might allow hackers remote access to devices.

Influenced by the news, the share price of the Hong Kong-listed Lenovo dropped by 1.1 percent and closed at HK$7.07 ($0.90) per share on Tuesday.

This is not the first time that the company has been shut out by developed countries.

The US Department of State initially planned to use 900 computers in its domestic safety network after procuring them from Lenovo in 2006. However, the plan was aborted following objections by some departments.

It was suggested that those computers would put national network security in danger.

The official background of Lenovo, with the government-backed Chinese Academy of Sciences owning a big portion of stake in the company, is believed as the main reason why it is mistrusted by Western governments.

Citing national security concerns, the Shenzhen-based telecommunications producer Huawei Technologies has been banned by the Australian government from bidding on a several-billion Australian dollar broadband contract.

Huawei is alleged to be connected to the People's Liberation Army. This has been denied repeatedly by the company.

"The so-called 'backdoor' problem has been exaggerated by Western countries for years, but it only exists on a theoretical basis," Xin Haiguang, an Internet observer, told the Global Times Tuesday, adding that no records of such security information leakage have been found.

For China, these bans only serve to hurt the principle of free trade, and these companies should learn to sue such protectionism in a bid to protect their reputation, Xin said.