SHORTLY after welcoming his new baby, ALEC BALDWIN ignited a new family feud!

The star infuriated his 17-year-old daughter Ireland for revealing on national TV that she had yet to meet her little sister nearly three weeks after her birth, sources told The ENQUIRER.

The 55-year-old “30 Rock” star and his second wife, 29-year-old yoga instructor Hilaria Thomas, had their first child together, Carmen, on Aug. 23. And during a Sept. 12 appearance on “Late Show with David Letterman,” big-mouth Baldwin revealed that Ireland hadn’t yet seen the baby and predicted their meeting would be awkward.

“It’s weird, you know?” the actor told Letterman. “We’re going to hand her this three-week-old baby and say, ‘This is your sister.’”

Stunned  by the statement, Ireland felt “really embarrassed,” said an insider, who added that she said her dad’s comment made her “look like some absentee big sister who doesn’t have time for family.”

Right after the interview ended, the insider says the leggy 6-foot-2 model called her dad and “told him she doesn’t want him talking about her because he always ends up putting his foot in his mouth.”

While Baldwin’s rep said, “Their relationship is great and the relationship with his daughter is great” father and daughter have had some rocky times since his bitter divorce battle with Ireland’s mom, Kim Basinger, was finalized in 2002. It made spectacular headlines in 2007 after Ireland failed to answer a phone call from him and an enraged Alec left a voice mail blasting his daughter as a “rude, thoughtless little pig.”

Ireland – who lives in L.A. with Kim while Alec is based in New York – has gone on to enjoy wonderful success as a model. But because of her hectic schedule, she hasn’t had time to meet her baby half sister.

However, the young beauty posted an online message for little Carmen, warning her: “You have been born into one crazy family. You are both lucky and cursed at the same time.”