The popular New York Times website returned to service on Wednesday after hackers forced it down for nearly a day, with a group backing Syria's government claiming responsibility.

The website nytimes.com, one of the most influential sources of news in the United States, had come up blank for many readers since Tuesday afternoon, though some were still able to access it earlier Wednesday.

Experts called it a complex attack, hitting not only the Times but also parts of Twitter, that demonstrated the talent of the hackers.

"It's a very sophisticated attack," said computer security expert Rob Enderle of the Enderle Group.

The paper directed readers via Twitter to a backup site while it tried to get the main site back up.

On Tuesday the Syrian Electronic Army (SEA), supporters of Assad who have hacked a number of media websites and their Twitter accounts, claimed responsibility for bringing down the Times website and interrupting the Twitter website as well.

"Media is going down," a message at the shadowy group's Twitter account proclaimed. "Twitter, are you ready?"

The group apparently directed the attack via an Internet domain name registry firm, Melbourne IT, that serves both the Times and Twitter.

The Australian company's own blog had only this message Friday: "Hacked by SEA, Your servers security is very weak."

Marc Frons, the Times chief information officer, said the outage was "the result of a malicious external attack" and also credited the Syrian Electronic Army, "or someone trying very hard to be them," the Times reported.

"Well, at least hackers in Syria think we're still central to American life," Times business reporter Binyamin Applebaum wrote on his Twitter account.

Twitter also pointed to an attack on its domain name registry. The hack attacks came as theUnited States geared up for possible military action against Assad's regime as punishment for a chemical weapons attack against civilians that Washington has blamed on the regime.

The SEA has made itself known in recent months, hacking the Twitter account of The Associated Press to put out a false tweet saying President Barack Obama had been hurt in two explosions at the White House.

SEA has also targeted the Twitter account of the AFP photo service, as well as social media at the BBC, Al-Jazeera and the Financial Times and Guardian newspapers.

On its own website, the SEA said it defends the Syrian Arab people from campaigns led by Arab and Western media.

Enderle said the group clearly had strong skills that it was putting on display.

"Attacks by government entities are very well funded and equipped and tend to be damaging," he said.

"They just wanted to give a warning, suggesting they can get into US infrastructure."