The New York Times said its website went down Tuesday after what appeared to be a "malicious external attack."
Times spokeswoman Eileen Murphy made the announcement on Twitter, two weeks after the site went offline due to what the daily said was an internal server problem.
Her full tweet said: "re: http://nytimes.com - initial assessment - issue is most likely result of malicious external attack. working to fix."
The newspaper's main Twitter account said shortly after 2000 GMT that its website "is experiencing technical difficulties" but was publishing news via Twitter and other links.
The daily said in January that hackers stole its corporate passwords and accessed the personal computers of 53 employees after the newspaper published a report on the family fortune of China's Premier Wen Jiabao.
The Washington Post website was hacked this month in an attack blamed on the Syrian Electronic Army, a group that backs embattled strongman Bashar al-Assad.
© AFP 2013