The New York Times Web site was unavailable to readers on Tuesday afternoon after an online attack on the company’s domain name registrar. The attack also forced employees of The Times to take care in sending e-mails.

The hacking was just the latest of a major media organization, with The Financial Times and The Washington Post also having their operations disrupted within the last few months. It was also the second time this month that the Web site of The New York Times was unavailable for several hours.

Marc Frons, chief information officer for The New York Times Company, issued a statement at 4:20 p.m. on Tuesday warning employees that the disruption — which appeared to be affecting the Web site well into the evening — was “the result of a malicious external attack.” He advised employees to “be careful when sending e-mail communications until this situation is resolved.”

In an interview, Mr. Frons said the attack was carried out by a group known as “the Syrian Electronic Army, or someone trying very hard to be them.” The group attacked the company’s domain name registrar, Melbourne IT. The Web site first went down after 3 p.m.; once service was restored, the hackers quickly disrupted the site again. Shortly after 6 p.m., Mr. Frons said that “we believe that we are on the road to fixing the problem.”