HBO has made viewers an offer they can't refuse -- a surprise sixth season of The Sopranos (search).

The popular mobster-on-Prozac drama was scheduled to end after its fifth season, which kicks off early next year.

But HBO and series creator David Chase (search) announced yesterday that there will be a sixth season of the most popular show in HBO's 20-year history.

Last season, The Sopranos averaged as many as 12 million viewers -- huge for a cable show. The fourth season's premiere was the highest-rated show in HBO history.

The sixth season, comprised of 10 episodes, will begin shooting in early 2005 -- a year after the fifth season wraps. All of the principal cast members -- or whoever doesn't get whacked next season -- are expected to return for the sixth season.

The Sopranos, which revolves around depressed North Jersey mobster Tony Soprano (James Gandolfini (search)) and his extended "family," is currently shooting the fifth season.

Production was delayed a few weeks when Gandolfini got into a contract dispute with HBO. But Gandolfini and HBO settled their differences, resulting in Gandolfini upping his per-episode fee to about $1 million and getting a cut of Sopranos DVD and syndication profits.

Gandolfini recently shared his newfound wealth with his fellow castmates - reportedly dipping into his wallet to dole out a total of $500,000 in cash as a way of saying thanks.

Last season, considered spotty by many Sopranos fans, was highlighted by the spectacular murder of troublemaker Ralph Cifaretto (Joe Pantoliano (search)), who was beaten to death by Tony and then cut into pieces after killing Tony's prized racehorse to collect insurance money.

Chase has also talked about writing a Sopranos movie, perhaps after the regular series ends its run.