Google has accused the Chinese government of interfering with its popular Gmail email system. The move follows extensive attempts by the Chinese authorities to crack down on the "jasmine revolution" – an online dissident movement inspired by events in the Middle East.

According to the search giant, Chinese customers and advertisers have increasingly been complaining about their Gmail service in the past month. Attempts by users to send messages, mark messages as unread and use other services have generated problems for Gmail customers.

In the wake of the catastrophic earthquake in Japan, Google set up an application to help people find relatives and friends lost in the disaster. This service too seems to have been blocked.

"Relating to Google there is no issue on our side. We have checked extensively. This is a government blockage carefully designed to look like the problem is with Gmail," said a Google spokesman. China's embassy in Washington was not immediately available for comment.

The announcement follows a blog posting from Google on 11 March in which the firm said it had "noticed some highly targeted and apparently politically motivated attacks against our users. We believe activists may have been a specific target." The posting said the attacks were targeting a vulnerability in Microsoft's Internet Explorer web browser. The two firms have been working to address the issue. At the time, Google declined to elaborate on which activists had been targeted or where the attacks had been coming from.

Last January Google said it had been the victim of highly sophisticated attacks originating from China. At first the firm thought its intellectual property was the target. The company's investigations found at least 20 other internet , financial, technology, media and chemical companies had been similarly targeted. Google said it had uncovered evidence that the primary goal of the attacks was the Gmail accounts of Chinese human rights activists.

The search firm is not commenting further on this latest attack, but technology experts said it seemed to show an increasingly high degree of sophistication. "In the wake of what is happening in the Middle East I don't think China wants to be seen making heavy-handed attacks on the internet, that would draw too much attention," said one internet executive who wished to remain anonymous. He said making it look like a fault in Google's system was extremely difficult to do and the fact that these blockages appear to come and go makes them look "semi-industrial and very, very sophisticated."

In February dozens of political activists were arrested in China after an anonymous call online for people to start a jasmine revolution. The crackdown came as China's president Hu Jintao called for tighter internet controls to help prevent social unrest. Much of the unrest in the Middle East has gone unreported in China, where the internet is already heavily censored. Facebook and YouTube are blocked in China. LinkedIn was temporarily disrupted last month.

Google first opened for business in China in 2005. But after announcing that it had been hacked in January last year the company said it was no longer prepared to censor its search results and moved its operations to Hong Kong.

"We want as many people in the world as possible to have access to our services, including users in mainland China, yet the Chinese government has been crystal clear throughout our discussions that self-censorship is a non-negotiable legal requirement," David Drummond, Google's chief legal officer, said at the time.

According to WikiLeaks cables, China's political elite have a love hate relationship with the internet. On the one hand the authorities want the information they can obtain via the web and on the other they are extremely concerned by the threat they perceive it presents to their authority. The cables suggest China has successfully hacked the US and other governments as well as private enterprises.

The leaked cables also chronicle the pressure put on Google to comply with Chinese censorship. As well as removing references to the Dalai Lama and to 1989's Tiananmen Square massacre, Google was asked to censor images of government facilities displayed on the Google Earth mapping service.

Last month the Chinese authorities launched Panguso, a search engine joint venture between Xinhua news agency and the state-owned telecoms giant China Mobile. The site appears to be even more heavily censored than Baidu, the largest search firm in China. Searches on Panguso reportedly produced no results for Nobel peace prize laureate Liu Xiaobo.

• This article was amended on 21 March 2011. The original said LinkedIn was blocked in China. The service was temporarily disrupted in February. This has been corrected.