Japan suspects its defence ministry and national police agency websites have come under cyber attack this week, a news report said Friday, amid a bitter row with China over a territorial dispute.

The government is looking into the attacks given that China's largest known hackers' group had warned it would attack Japanese government websites until Saturday in protest over the maritime incident, Kyodo News agency reported.

The defence ministry and national police agency websites became difficult to access, possibly because of cyber attacks, between Wednesday and Friday, unnamed government officials were quoted as saying.

The method of attack was believed to be a so-called distributed denial of service attacks, in which a group of hackers flood a target website with a mass of data, slowing it to a crawl, the official was quoted as saying.

The defence ministry said access to its website surged for about half an hour Wednesday evening and the police agency said access to its website slowed considerably overnight from Thursday to early Friday.

The news report also said the government had called on municipal governments and public universities to increase surveillance of their websites and check their responses in case hackers launch an attack on their sites.

Japan and China are embroiled in their worst spat in years, stemming from the September 7 collision of a Chinese fishing trawler and two Japanese coastguard vessels near a disputed island chain in the East China Sea.

China has so far summoned Japan's ambassador five times over the incident, cancelled a senior lawmaker's Tokyo visit and repeatedly demanded the boat's captain be released from Japanese custody.

It has also resumed unilateral work on a gas field in a disputed maritime territory, after scrapping talks on its joint exploitation with Japan.

Japan has called the situation "extremely regrettable". Its officials also say there are no plans for the prime ministers of the two countries to meet next week on the sidelines of a UN summit in New York.

earlier related report
Cybercrime is world's most dangerous criminal threat
Hong Kong (AFP) Sept 17, 2010 - A crime epidemic is silently sweeping the globe as criminals turn our ever-increasing dependence on computers against us, and even the head of Interpol is not immune.

On Friday 300 of the world's top law enforcement officials concluded the first ever international police anti-cybercrime conference, facing the stark and growing threat from an estimated 105-billion-dollar illegal business.

And Ronald K. Noble, secretary general of the international police agency Interpol, told the cream of law enforcement from 56 countries that his identity had been "stolen" to create two Facebook profiles.

One of the impersonators used the fake profile to obtain information on fugitives targeted in a recent Interpol-led operation seeking on-the-run criminals convicted of serious offences, including rape and murder.

"Cybercrime is emerging as a very concrete threat," he said at the opening ceremony of the first Interpol Information Security Conference at Hong Kong's police headquarters on Wednesday.

"Considering the anonymity of cyberspace, it may in fact be one of the most dangerous criminal threats we will ever face."

And terrorists could also inflict a significant blow with a cyberattack on a nation's infrastructure, he added.

"Just imagine the dramatic consequences of an attack, let's say, on a country's electricity grid or banking system," he said.

"We have been lucky so far that terrorists did not -- at least successfully or at least of which we are aware -- launch cyberattacks.

"One may wonder if this is a matter of style. Terrorists may prefer the mass media coverage of destroyed commuter trains, buildings brought down, to the anonymous collapse of the banking system. But until when?"

The scale of the problem was also highlighted at the Asia launch of a new report, also in Hong Kong, on Thursday by Internet security firm Symantec.

Almost two thirds of all adult web users globally have fallen victim to some sort of cybercrime, the 2011 Norton Cybercrime Report: The Human Impact study says, from spam email scams to having their credit card details stolen.

China had the most cybercrime victims, at 83 percent of web users, followed by India and Brazil, at 76 percent each, and then the US, at 73 percent.

The study, of over 7,000 Internet users, also found that 80 percent of people believed the perpetrators would never be brought to justice. Fewer than half ever bother to report the crime to police.

Stacey Wu, a Symantec senior director, told AFP that just one of the firm's offices -- in Chengdu, China -- alone detects 100,000 cybercrime threats every single day.

"It is no longer just high school kids in their bedrooms sending out malicious emails," she said. "It's organised criminals.

"They carry out silent, hit-and-run attacks that steal relatively small amounts of 20 dollars or so from 20 or 30 people. Then they move on."

Cybercriminals also trade in data stolen, often unnoticed, from a victim's computer. Credit card details, for instance, are sold on the black market for between five and 20 dollars.

"Identity and personal information theft is a big problem," Wu told AFP. "For example, if the criminal knows a person makes a lot of transactions online, the value of that person's information can be worth a lot more."

Cybercrime is worth an estimated 105 billion dollars, according to rival computer security firm McAfee, and US police say cybercriminals can earn around 23,000 dollars a week.

The biggest problem, and the criminal's greatest advantage, is complacency, says Professor Joseph Kee-Yin Ng, treasurer of the Internet Society Hong Kong.

"It is hugely important for people and companies to protect themselves," he told AFP. "The criminal is as real as any thief or mugger, you just can't see them."