The suspense series "24" (search) is embroiled in a nail-biter of its own over its renewal for next season.

With less than two weeks to go until FOX (search) unveils its new fall lineup May 19, the future of "24" is the subject of intense negotiations between the network and the series' producer, Twentieth Television, a unit of the same parent company, News Corp., which also owns The Post and FOXNews.com.

And there's an added wrinkle: NBC (search) is also interested in "24," The Post has learned.

"I can tell you that NBC has not been shy about expressing their interest in '24,' " said a source who requested anonymity.

The issue is money. Unlike previous renewals, this one is complicated by the fact that FOX's initial four-year license term for "24" expires with the end of the current season (the finale airs May 23).

When a license term expires, the price goes up.

"Essentially, the price tag for a series generally goes up dramatically after being on the air for four years," a source explained.

The tug-of-war over "24" comes as the "real-time" series — starring Kiefer Sutherland (search) as a federal anti-terrorism agent — is enjoying its best ratings ever. With just shy of 12 million viewers per episode this season (according to Nielsen), "24" is the second-highest-rated drama series on FOX (after "House").

But instances of TV series switching networks are rare. And while NBC's intrusion in the negotiating process might drive up the price of a fifth season of "24" even more, the odds favor FOX making a deal to keep the series.

Officials of FOX and Twentieth Television declined comment.