U.S. late-night programming has become must-see TV as NBC's current kerfuffle involving hosts Jay Leno and Conan O'Brien is getting daily skewering by — who else — late-night TV hosts.

David Letterman (CBS), Jimmy Kimmel (ABC) and Craig Ferguson (CBS) are among those chiming in nightly with jabs, while the two hosts at the centre of the mess are also constantly cracking bitter jokes about the situation.

On the weekend, NBC revealed its intention to axe the experiment of moving former Tonight Show host Leno to the 10 p.m. weeknight prime-time slot and introduce a shortened version of the new show at 11:35 p.m., following the evening news.

The decision was prompted by the network's outraged affiliate stations, which said they had been losing masses of viewers since the program debuted in September.

On Monday, O'Brien rejected the move as it would shift his program to after midnight, adding that he would not participate in the "destruction" of the venerable Tonight Show's legacy.

Sharper jabs

While the situation has been fodder for the comics all week, the comics' various monologue jokes had largely been centred on blaming NBC for the mess. However, on Wednesday night, the two NBC hosts seem to have turned against each other.

Leno noted O'Brien's complaint earlier this week that NBC's top brass only gave him seven months to establish himself on Tonight.

"Seven months!" Leno said. "How did he get that deal? We only got four."

For his part, O'Brien said in his monologue that serving as host of Tonight had fulfilled his lifelong dream.

"And I just want to say to the kids out there watching: You can do anything you want in life," he said. "Unless Jay Leno wants to do it, too."

Veteran late-night host Letterman — who had competed against Leno for the Tonight chair in 1992 and whose former NBC slot was eventually inherited by O'Brien — offered a timely quip Wednesday night.

"Isn't it lousy cold outside today?" Letterman said. "You know, they say, from the weather bureau, they say it's caused by an Arctic chill between Jay and Conan."

Several late-night hosts, like Letterman and Ferguson, appear to be siding with O'Brien, as have many celebrities and thousands of members of the public, with "Team Conan" groups emerging across social media online.

Dramatic loss of key viewers: report

Meanwhile, research firm Harmelin Media released a report Wednesday that showed how dramatically NBC's decision to cut out five hours of dramatic programming on weeknights and insert The Jay Leno Show has hurt the local news broadcasts of its affiliate stations.

The study found local stations saw their 11 p.m. news audiences drop by an average of 25 per cent in November (compared to November 2008) in the highly influential 24- to 54-year-old viewer demographic, upon which advertising rates are based.

In some key markets, the drop was startling: in New York, the decline was 48 per cent and in Los Angeles, 43 per cent.

Television insiders are forecasting that O'Brien will likely leave NBC after negotiating some kind of settlement.

Rival network Fox, which lacks a late-night talk show, has a history with O'Brien, formerly a much-lauded writer for animated stalwart The Simpsons.

Earlier this week, Fox Entertainment president Kevin Reilly (who himself was ousted from NBC a few years ago) expressed interest in O'Brien, calling him "a very compatible fit for our brand."

With files from The Associated Press