I beg your pardon.

Meaning

A formal apology, often for interrupting.

Examples

• John: Excuse me, did you say something?
• Alice: I said it's time for lunch. <b>I beg your pardon</b>, did I interrupt you?
• John: No, not at all. Thanks for reminding me.
• Alice: You're welcome. <b>I beg your pardon</b> if I startled you.