The head of the newspaper's information, Mark frons, the New York Times warned employees attack was carried out by the Syrian Army Electronic parts that support Assad, "or someone trying to be them."
He reminded the staff to "be careful when sending communication through e-mail until the situation is resolved."
Cyber Warfare
Security experts say there is enough evidence to link these accusations.
"Domain address pointing NYTimes.com SyrianElectronicArmy.com that its IP address is in Russia, so obviously this is a malicious attack," Ken Westin, a security researcher for Tripwire, an online security company told the BBC.
In a separate post on Tuesday, the group also claimed responsibility belongs Twitter has been hacked information.
More recently, Washington Post, CNN and Time were targeted in attacks attributed to the group supporting it.
"The attack appears to be increasing and the media is more than just an annoying nuisance, and if successful will put millions of users in situations NYT site is full of risks," says Westin.
As happened after the first attack, their competitors, namely Wall Street Journal paid lower costs and offer free content to all visitors.
In January, the New York Times said the hackers had managed to access internet sites and stealing passwords of 53 employees after the newspaper published a report on China's Wen Jiabao family's wealth.