Nearly 3,300 computer viruses were discovered in the country in July alone, according to the network security firm Bach Khoa Internet Security Centre (BKIS).

"Almost all of these viruses were from foreign countries, including the US, Russia and China. Only three came from Viet Nam," BKIS said.

"The viruses infected 5.3 million computers in Viet Nam. Most damaging of the viruses was the W32.TedrooG.Worm, which attacked more than 81,000 computers," BKIS added.

BKIS also reported that about 89 big agency and company websites in Viet Nam were hacked into in July.

Of the affected websites, 16 were infiltrated by domestic hackers and 73 others were infiltrated by people from foreign countries.

BKIS discovered that 183,000 Vietnamese computers were affected by about 113 viruses in July which prevented users from accessing anti-virus websites and software.

During that time, many web surfers were unable to access the websites anti-virus software companies while they were still able to access other websites.

"After infecting computers, these viruses started to prevent all access to anti-virus websites and software, meaning users were unable to download and upload anti-virus software," said Vu Ngoc Son, Director of BKIS R&D.

"By preventing people from updating anti-virus software, viruses will be able to steal private information, bank account numbers and online game accounts," said BKIS.

"When infected with a virus, users should not try to repair their computers by themselves. They must contact anti-virus software producers for support to avoid damage," warned BKIS.