WASHINGTON (AFP) ― The Washington Post disclosed Saturday that it had suffered a cyberattack and suspects Chinese hackers were behind it, joining Twitter and major U.S. media outlets that have endured intrusions.

The Post said in a front page story that the attack was detected in 2011.

It said Post company officials would not comment on the circumstances, duration of the intrusion or apparent origin of the online attack.

The paper quoted Post spokeswoman Kris Coratti as saying the paper worked with a security company to detect, investigate and resolve the situation “promptly” at the end of 2011.

“We have a number of security measures in place to guard against cyberattacks on an ongoing basis,” Coratti was quoted as saying.

The attack coincided with the revelation of several high-profile security breaches.

The New York Times and The Wall Street Journal said last week that they had been hacked, and pointed to attackers from China.

The two dailies accused Chinese hackers of targeting their computers in an apparent effort to spy on journalists covering China.

Meanwhile, Twitter said Friday that it too had been hammered by a sophisticated cyber attack similar to those that recently hit by the media outlets.

The popular microblogging site said the passwords of about 250,000 users were stolen, but did not confirm the source of the intrusion.

“This attack was not the work of amateurs, and we do not believe it was an isolated incident,” Twitter information security director Bob Lord said in a blog post.

And the New York Times reported last week that the Bloomberg news agency was attacked by Chinese hackers after it published an article last June about wealth accumulated by relatives of Beijing’s then-vice president Xi Jinping, who is expected to become China’s president in March.