Expats Living in Shanghai

Over the past few weeks, access to Gmail has been intermittent for users inside , and some foreign journalists have reported that their accounts have been hacked into.

The problems have coincided with what appears to be an intensified campaign by the authorities to control the internet, following the unrest in the Middle East and a series of calls on the web for a similar "Jasmine" revolution in China.

Google said its engineers could find no technical problems with Gmail or its main website.

"There is no technical issue on our side; we have checked extensively. There is a [Chinese] government blockage carefully designed to look like the problem is with Gmail," the company said in a statement.

Two weeks ago, Google also said that it had noticed "some highly targeted and apparently politically-motivated attacks against our users" in China. "We believe activists may have been a specific target," it added.

Google decided to close down its mainland China website and relocate its operations to Hong Kong following a series of attacks from Chinese hackers at the end of 2009.

The hackers stole some Google source code and also gained access to the private Gmail accounts of Chinese human rights advocates.

The Chinese Foreign ministry had no immediate comment on Google's statement.

Meanwhile, computer analysts also said that China has rolled out a new layer of censorship infrastructure to prevent internet users inside China from "jumping over" the Great Firewall.

Until now, internet users, including many businesses inside China, have established private networks which help them circumvent censorship and send information confidentially.

However, several companies providing these "virtual private networks" have reported that their systems have been nullified in the past week.