A pair of QUEEN ELIZABETH'S panties were supposed to hit the auction block . . . but the sale has been put on hold due to the upcoming royal wedding.

It sounds like a late April Fool's joke, but it's for real. The panties were left on a plane way back in 1968 . . . and became the property of a collector.

Auctioneer Charles Hanson had planned on buying the panties and putting them on the block. But he has decided to delay the sale until after PRINCE WILLIAM gets hitched.

He's doing it out of, quote, "respect and courtesy for a person of such dignity and rank."

For those of you who have been dying to get a hold of the Queen Mum's delicates, you're going to have to suck it up and wait just a bit longer.

Check out a picture of the panties here. Elizabeth would have only been about 42 in 1968, but these things are the very definition of GRANNY PANTIES.

My question is what celebrities panties would you buy and what's the most you would pay for them?

TMZ