"The Tonight Show" host Jay Leno called NBC executives "snakes" in Monday's monologue. Reuters

Late-night television-show host Jay Leno made a series of jokes mocking NBC’s ever-falling ratings last month, and it appears executives at the network are furious about it.

During “The Tonight Show with Jay Leno” Feb. 28, the comedian made numerous mocking stabs at NBC’s extreme drops in the ratings.

“For the first time in history, NBC is going to finish fifth in the ratings period,” the New York Times quoted Leno as saying. “We are behind the Spanish-language network Univision -- or as we call it here in Los Angeles: Cinco de Ratings.”

Leno then rapidly fired off a series of Johnny Carsonesque one-liners: “It’s so bad, ‘The Biggest Loser’ isn’t just a TV show anymore; it’s our new motto ... It’s so bad, NBC called Manti Te’o and asked him to bring in some imaginary viewers ... The most common thing people are giving up for Lent? Watching NBC.”

The New York Times reported NBC executives were incensed by Leno’s mocking and that there was “an exchange of pointed emails” between NBC Entertainment Chairman Robert Greenblatt and the comedian over Leno’s on-air treatment of his home network.

Times writer Bill Carter, who has covered the late-night TV comedy wars extensively, noted that Leno seemed shocked by Greenblatt’s ire. Carter also described the long-standing tradition of late-night hosts poking fun at their networks dating all the way back to Carson’s gig on “The Tonight Show.”

This heated battle between Leno and NBC executives has also stirred rumors that Leno will soon be retiring and leaving “The Tonight Show” to a new host, most likely Jimmy Fallon. NBC execs are reportedly threatened by “Jimmy Kimmel Live’s” outstanding performance in the same time slot and are hoping that Fallon’s fresh blood will goose the ratings.

"Kimmel has done extremely well. Jay wins overall, but, on any given night, it's neck-and-neck [among those ages] 18-49. I understand where they might have fear and also feel that they own the solution [in Fallon]," a network veteran told the Hollywood Reporter.

Of course, the rumors of Leno leaving are far from a sure thing. While Kimmel has indeed done extemely well in the coveted 18-49 age demographic, Leno is still beating his competitors in the late-night market. At the same time, it could be an extremely risky move for NBC to get rid of one of its highest-rated late-night shows during such a difficult struggle for viewers.

Watch Leno's mocking remarks about NBC's performance in the ratings below, courtesy of Hulu and Yahoo: