Baseball players and owners have reached an agreement on a tougher steroid-testing program and plan to announce it today, the Associated Press has learned.

The agreement will include penalties for first-time offenders, an AL player said on condition of anonymity. Other details, such as the frequency of tests, were not immediately available.

Commissioner Bud Selig, asked about a steroid agreement at the owners meeting in Scottsdale, Ariz., declined comment but did say: “We’ll have announcements to make tomorrow.”

“I’m glad we could come to an agreement,” said Chicago Cubs pitcher Mike Remlinger, who was briefed on the deal yesterday. “It was the right thing to do. I think it was something that needed to be done, and I think players understand it needed to be addressed.”

The sides spent the past month negotiating the deal after the union’s executive board gave its staff approval to pursue an agreement on a more rigorous testing program. Some in Congress threatened to take action unless baseball reached an agreement on its own.

“I think it’s going to entail more testing, some out-season testing, yes, more in-season random testing and stiffer penalties,” said Mets pitcher Tom Glavine, a senior member of the union.

Bob DuPuy, baseball’s chief operating officer, said he anticipated confirmation of a deal by the end of the owners’ meeting.

“It will be wonderful once it’s done, but I don’t want to pre-empt any announcement, and I certainly don’t want to pre-empt all the work the commissioner has done on this, so I’ll reserve my comments until after it’s announced,” he said.

Players and owners agreed to a drug testing plan in 2002 that called for survey-testing for steroids the following year. Because more than 5% of tests were positive, random testing with penalties began last year.