Even working on her laptop in Amnesty International's London headquarters or talking on her mobile phone going around the city, Corinna-Barbara Francis suspects Chinese authorities are listening in.

At a time when authorities in Beijing are carrying out the most serious crackdown on dissent since Tiananmen Square, the human rights group's China researcher says she simply assumes all her electronic data is already compromised.

Whether or not she is right is almost impossible to know. Beijing angrily denies any suggestions of official complicity in a string of recent high-profile computer hacks including Internet giant Google, which said it traced an attempt illicitly to access accounts of activists and others to China.

We get dozens of attempts every day -- viruses and worms -- trying to attack our systems, Francis told Reuters, saying many appear to originate in China though proving it was much harder. I simply assume that everything is being read. I would not keep the name of a particularly sensitive contact on my laptop, send it by e-mail or discuss it by phone.

Such tradecraft has long been common among activists operating in authoritarian states. The difference now, she says, is that the borderless nature of the Internet means activists assume the reach of state spies from sophisticated authoritarian states now extends into the very fabric of western nations.

Even in the UK, the phone system is not beyond the reach of the Chinese government, she said. I might write a name down... with paper and pen but often I won't even do that.

One colleague, she said, was so nervous that she would not discuss sensitive material anywhere near a mobile phone anywhere in the world unless its battery was removed, for fear it has been hijacked as a listening device.

Security experts disagree on how realistic such fears may be. The bottom line, they say, is that any sophisticated state in the 21st century has formidable powers to read almost any electronic information it wishes. So do a rising number of independent hackers, despite ever-tightening security systems.

The International Monetary Fund (IMF) this weekend became the latest organization to say it was probing an attempt to access its data and some security experts suspect a nation state.

A rising number of major companies -- including Sony, defense giant Lockheed Martin and Citigroup -- have also suffered high-profile hacking attempts.

Some have been tentatively traced to China, where security experts suspect authorities both turn a blind eye to hackers and sometimes use them for their own ends. Others appear linked to western antiestablishment hackers such as Anonymous.

Some western intelligence experts suspect China's rulers are also keen to make sure young computer experts are kept focused on internal or external enemies rather than be tempted to hack the computers of those in charge in Beijing. Chinese officials say they are also victims of hacking, say western states too have failed to eradicate criminal computer activity on their turf and call for all countries to work together to produce a more regulated, safer Internet.

POST-ARAB SPRING CRACKDOWN

But with data stolen ranging from commercial secrets to customer details, experts say firms may have to get used to making the same assumptions about state surveillance and hacker penetration that activists have long accepted.

At the very least, they should be more alert for attacks.

Cui Weping, a professor at the Beijing Film Academy who has spoken out against restrictions on freedom of speech and other issues, said her Gmail account was among those briefly locked by Google apparently because it had been hacked.

This has happened before, she said. My Gmail account is suddenly inaccessible because my password has been changed... and then I can't open it. Who knows what they are after?

China has long focused on trying to control dissent and debate on the Internet and within its borders. Surveillance is widespread, websites such as Twitter are blocked and officials keep close tabs on officially run social media platforms.

Western spy agencies too are widely assumed to monitor e-mails and telephone calls, primarily to track militants and criminals, but most experts believe China is able to devote many thousands more intelligence agents to the task.

Since the Arab Spring brought revolution to Tunisia and Egypt, Chinese officials seem to have become much more nervous.

Arrests have increased -- including some of individuals providing information to human rights groups and whose identity is believed to have been detected from e-mail or phone taps.

As in Russia -- another authoritarian state where those in power are seen concerned about online dissent -- dissident websites have come under more cyber attacks this year.

There have long been suspicions of massive Chinese state spying on dissidents and others. In a 2009 investigation into computer malware and hacking into computers, the civil society group Information Warfare Monitor uncovered a network of hundreds of infected computers they dubbed Ghostnet.

Its report said that whoever the hackers were, they were operating from Chinese servers, recording keystrokes and activating microphones and webcams to turn computers into bugging devices.

But some say many online intelligence gathering efforts are much less sophisticated, and often easily detected.

When I opened my inbox there was a prompt telling me to enter my personal information for safety purposes and to change my password and fill in a forwarding e-mail address, said one China activist on condition of anonymity, saying it was one of several e-mails apparently intended to trick the recipient into giving up access details or downloading malware. I ignored it.

(Additional reporting by Beijing bureau, editing Tim Pearce)

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