Major league baseball players went on strike tonight, after negotiations that lasted most of the day failed to produce an agreement.

Negotiations continued past the 7:35 p.m. strike deadline. The third session lasted less than an hour, after which Bob Fishel, a spokesman for Lee MacPhail, chief negotiator for the owners, said the talks would reconvene at 9:30 a.m. Wednesday. Today's sessions totaled 11 hours.

"Lee expressed the opinion that they had made some progress -- not overwhelming -- but some progress, especially in the area of salary arbitration and the benefit plan," Fishel said.

Donald Fehr, acting executive director of the Major League Players Association, got in the last word late tonight after the third meeting. In response to the statement from MacPhail, the union leader said, "I understand why they would want to put the best face on it. But we ought not to minimize where we are, and where we are is that we've got a strike."

Before the day's final session, Fehr had said, "I understand there were rumors circulating that said we are close to an agreeement. If that was true, then (the owners) have been negotiating with somebody else. I have never said we are close to an agreement, and I have never thought we are close to an agreement. The fact is that we're still hung up on salary arbitration and the salary cap issues."

Fehr said there was some discussion of pension contributions but no significant progress.

"The pension situation has narrowed somewhat," he said. "But it was nowhere near enough."

Buck Martinez of the Toronto Blue Jays, the American League players' alternate representative, said there would be resistance if the union gave in on the question of limiting salary arbitration awards or a salary cap in general.

"I'm a player from the pre-1976 (Andy) Messersmith era," he said. "We're finally to the point where we can have fair market value for players, and I don't think we would want to restrict that."

Representatives of owners and players met for more than five hours earlier today, breaking to announce there would be a strike and then going back into session at 5:30 p.m. By then, baseball was only two hours away from its first games of the evening, including the Baltimore Orioles against the Blue Jays at Exhibition Stadium in Toronto, and it obviously was too late to save the day's 13-game schedule.

The sides still have not agreed on the two main issues: salary arbitration and the owners' contribution to the players' pension fund.

Salary arbitration seems to be the more difficult issue to solve. That's because it involves conflicting principles that each side holds dear. The owners' contribution to the pension fund, which traditionally has been one-third of the network television package, also is a disputed topic. But that seems to have become a question of finding an acceptable figure to replace the one-third portion, which the owners consider out of the question since the television contract that went into effect in 1984 is worth $1.1 billion over six years.

The current salary arbitration system allows a player to be eligible after two years of major league service. The union originally had wanted to expand eligibility to include exceptional players with less than two years of service, but dropped that demand Sunday.

The owners see salary arbitration as a major contributor to the financial trouble they claim to be fighting. They want to raise the eligibility requirement to three years and place a 100 percent limit on the amount of salary increase an arbitrator can award.

Last week, the owners proposed an increase in the pension contribution from $15.5 million per year to $25 million, but the increase would be limited if players' salaries rose above a certain level. The players rejected that proposal and the modified one -- which set a minimum contribution -- offered by the owners Sunday because it included the owners' salary arbitration proposal.

The union proposed its pension solution Sunday, saying it would accept about $40 million a year instead of $60 million. But the union said the $20 million difference had to be used to help the teams that the owners contend are in financial trouble. The owners rejected that plan because it included the union's salary arbitration demand.

After today's early sessions, Fehr said, "The owners insist on having artificially low maximums on players' salaries, (so) that there will be a salary cap on the overwhelming majority of players. Players could not test their value in a free market and have an impartial vehicle to determine their salary."

The owners have said they don't want to stop the increase in salaries, just slow the pace. But Fehr said their proposal would not assure the increases would continue.

"In our opinion, their proposal would affirmatively lower salaries," Fehr said. "They say that is not the case, that they just want to retard the rate of increase. So we said that if that is the case, you ought to give us some guarantees that it won't happen. But they wouldn't do it."

Kent Tekulve of the Philadelphia Phillies, the National League representative for the players union, said the union would hang tough.

"We're going to do what is right," he said. "And however long that takes, we're going to do it."