WASHINGTON — The New York Times Co. said Thursday it has signed up more than 100,000 paid subscribers for NYTimes.com since it began charging for full access to the newspaper's website three weeks ago.

The Times Co., reporting its first quarter results, also said net profit plunged 57.6 percent during the quarter to $5.4 million on continued weakness in the US print advertising market.

Revenue at the Times Co., which includes the flagship New York Times, The Boston Globe, the International Herald Tribune and a dozen other dailies, fell 3.6 percent to $566.5 million.

Print advertising revenue declined 7.5 percent in the quarter while digital advertising revenue grew 4.5 percent.

"The advertising marketplace faced increased pressure in the first quarter," Times Co. president and chief executive Janet Robinson said, adding that the operating performance "reflects the continuing transformation of our company."

"While the challenges for our company and for the larger economy are not yet behind us, the recent launch of Times digital subscription packages on NYTimes.com and across other digital platforms brings our plan for a new revenue stream to life," she said.

The Times Co. said digital subscribers for NYTimes.com have "surpassed 100,000" and "early indicators are encouraging."

The New York Times began charging online readers on March 28. The Times is offering readers 20 free articles a month at NYTimes.com before they will be asked to sign on to a digital subscription plan.

Like other US newspapers, the Times has been struggling with declining print advertising revenue, falling circulation and the migration of readers to free news online.