Yahoo e-mail accounts belonging to foreign journalists appeared to have been hacked and Google's Chinese search engine was intermittently blocked Tuesday, the latest troubles in China's heavily censored Internet market.

The Yahoo Inc. accounts of at least three journalists and an analyst became inaccessible over the last few weeks. They were greeted with messages saying, "We've detected an issue with your account" and were told to contact Yahoo, they said Tuesday. Yahoo techs told one of the four that his account had been hacked and restored his access, but it was not clear if the other instances were related.

Sensitivity about Internet security has run high since Google Inc. announced in January it might leave China after a series of cyberattacks and complaints about censorship. Last week, Google made a partial retreat, shutting down its mainland-based search engine and redirecting those queries offshore, to the freer Chinese territory of Hong Kong.

Analysts have been watching closely to see if China retaliates for Google's high-profile departure from the mainland search engine market.

Many redirected queries appeared blocked Tuesday on the Hong Kong-based search engine. Searches for benign terms were met with results on Chinese competitors such as and, however, an error page would pop up when typed into

Dozens of China-based Twitter users posted updates saying they were having the same problem. But it wasn't immediately clear what was causing the glitch.

Zhou Shuguang, a Beijing-based writer who blogs under the name "Zuola," said he tried to search the word "pest" using several search engines. Only returned an error message.

"'The connection was reset,' it says. It's the same for all the terms I put in," said Zhou. He thought it might be a technical problem but if it isn't fixed in a day or so, "then maybe it means China has blocked it."

Beijing-based Google spokeswoman Marsha Wang said she would look into the reports but didn't immediately respond.

It was not clear where problems with the Yahoo e-mail accounts originated from. All four people affected are professionally focused on China and related issues. They said they had heard of other colleagues having similar problems, including one journalist who lost his Yahoo account entirely in January.

Clifford Coonan, China correspondent for The Independent and the Irish Times newspapers, said he received the "issue with your account" notice when he logged in Tuesday. Another reporter said she received repeated error messages from Yahoo last month.

The Western analyst said he was locked out of his account for four or five days, until he spoke with a Yahoo representative Monday who went through the security questions and restarted it.

"He said somebody had hacked into my registration details," said the analyst, who would not give his name citing the sensitivity of the issue. The analyst said he was concerned hackers may have also accessed his inbox.

Yahoo officials in Asia and London declined to comment, referring queries to headquarters in Sunnyvale, California.

"I'd just be interested to see if anyone in the business community or outside of journalism and academia has had the same problem, then it might be less sinister," Coonan said. "It's obviously annoying but if it's just journalists and academics, that's scary."