The long-running crime drama Law & Order has been cancelled, with NBC confirming today that it had brought the curtain down on the series after a 20-year run.

The cancellation will result in the series wrapping up with the final episode of the current season, which airs on NBC on 24 May. The end of the series also means that it will have to settle for a tie with Gunsmoke as the longest-running prime-time drama in US television history.

Speculation about the future of the series has simmered for months, and its cancellation had been widely expected despite eleventh-hour negotiations between the network and Dick Wolf, Law & Order's creator and executive producer, over the possibility of extending the show into a 21st season. The current series has rated poorly, attracting an average audience of 7.3 million, well down on the peak of 18.7 million that it achieved for its twelfth season in 2001-02.

NBC had reportedly informed the programme's actors and producers of the decision on Thursday, although discussions with Wolf continued after that announcement had been made.

In a statement, NBC Universal's Jeff Gaspin said that the series had made a critical contribution to NBC's history.

"The full measure of the collective contributions made by Dick Wolf and his Law & Order franchise over the last two decades to the success of NBC and Universal Media Studios cannot be overstated.

"The legacy of his original Law & Order series will continue to make an impact like no other series before."

Highlighting that legacy was the reminder that the cancellation of the original Law & Order series is far from the end for the heavyweight franchise which it engendered. NBC confirmed on Friday that it had ordered production of a new series, Law & Order: Los Angeles (dubbed "LOLA"), and has also renewed the longest-running spin-off, Law & Order: Special Victims Unit, for a twelfth season in 2010-11.

You can discuss this story on our forums (register to post). Don't forget to check out the full details of what's staying and what's been cancelled in our 2010-11 season discussion.