Major League Baseball commissioner Bud Selig said he intends to take a close look at the Marlins’ blockbuster trade, which has set off a firestorm of protest in South Florida.

But sources said it’s highly doubtful he will do anything to stop it.

“I’m aware of the anger. I am,’’ Selig said Thursday in Chicago at the quarterly owners meetings. “We have this entire matter under thorough review.’’

In trading five of their frontline players to the Toronto Blue Jays, the Marlins shed more than $160 million in future salary obligations after only one season in their new ballpark.

The trade is not sitting well with fans and, according to sources, Selig and other owners. Selig, who argued for Miami’s new ballpark, is said to be upset with the team’s massive sell-off of players.

"My job is to do what’s in the best interest of baseball," Selig told reporters. “People have different views of that, on what you should do, and how you should do it. I’ve spent a lot of time on this.”

It’s within Selig’s power to attempt to nix the deal if he feels it’s not in baseball’s best interest. But industry experts don’t see that happening because of the precedent it could set.

Clearly, though, he’s concerned.

“I know what the commissioner can do, can’t do, what his legal responsibilities are, and other things,’’ Selig said. “I understand all of that. I understand the feeling. People ask me, ‘Don’t you wish it never happened?’ There are a lot of situations that I wish didn’t happen. I have to do what I have to do.’’

The teams haven’t yet presented the trade to Selig for his approval as the 12 players involved in the massive exchange continued to complete routine physicals. A deal might not be completed until next week, especially if Selig intends to give it a careful review.

The commissioner’s office is not the only concerned entity. The players union is also keeping a close eye on the situation in Miami and, in particular, the Marlins’ payroll. A few years ago, the Marlins signed an agreement promising to increase payroll when concerns were raised by the union that the team wasn’t using its revenue-sharing money on salaries. The union has already been in contact with the league about the Marlins’ latest sell-off.

“We’re monitoring it closely,’’ union spokesman Greg Bouris said.

Meanwhile, the Marlins remained on the defensive as angry fans took out their frustration on message boards and radio airwaves.

Marlins president David Samson was subjected to an onslaught of criticism when he answered fans questions Thursday on his weekly radio show with 790 The Ticket host Dan LeBatard.

“This isn’t fun for everyone,’’ Samson said. “The fun part is winning. I am, of course, remiss. I don’t want to lose fans or lose the trust. It’s hard sometimes to rip a Band-Aid off.’’

The Marlins are defending the moves by saying the team’s $95 million payroll was money down the drain as that team finished in last place with 93 losses. Their solution: tear it up and start over.

“I really hope that, over time, we’ll look back on these times and say this was a very painful time, but that it worked out, just like the ballpark debate, which was very painful like it is in every city,’’ Samson said.

Samson added that pitcher Ricky Nolasco, whose $11.5 million salary for next season would make him the highest-paid player on the team, would not be traded.

The ramifications from the latest fire sale could be vast.

One player’s agent with a large firm said it will be extremely difficult for the Marlins to attract free agents in the future, not after trading off Mark Buehrle and Jose Reyes so soon after giving them long-term contracts. The Marlins, per team policy, refused to include “no-trade’’ protection in either player’s contract when they worked out their deals.

“No one’s ever going there again,’’ said the agent, who agreed to comment only if his name was not used. “They’re going to have to overpay by 25 percent to get guys to come there now. They basically took the no-trade clauses and stuck them up Reyes’ and Buehrle’s [butt]. There’s no integrity in anything that they do and anything that they’ve said.

“They’re the laughingstock of baseball,’’ the agent continued. “Miami is now baseball’s Siberia.’’