Real Housewives of New York -- FAT RAISES ... OR WE QUIT!!

The Real Housewives of NYC have banded together against the Bravo Network -- REFUSING to continue on the show unless they ALL get huge raises, TMZ has learned.

Sources tell us ... LuAnn de Lesseps, Carole Radziwill, Aviva Drescher, Ramona Singer, Sonja Morgan and Heather Thomson were recently approached by Bravo individually with contract offers to appear on Season 6, which is supposed to begin production on Monday.

But the women were each unhappy with the offers ... and figured they would have more leverage against the network if they teamed up ... just like the cast of "Friends" did back in the day.

We're told the women approached Bravo as a group and made their demand clear -- FAT RAISES FOR ALL ... OR WE QUIT.

Here's where it gets interesting -- sources tell us the network is FURIOUS ... and has told the group they have until Friday (tomorrow) to sign the offers that are currently on the table, or they're all FIRED.

Translation -- IT'S A STANDOFF!!!!!

One thing to consider -- Season 5 of "NYC Housewives" was one of the lowest rated seasons in the show's run.