The SAG-AFTRA war over jurisdiction has amped up, with AFTRA threatening to ditch SAG and go it alone at upcoming contract negotiations.

The American Federation of Television & Radio Artists issued the warning Monday — with both unions starting to prep for what are expected to be complex and contentious negotiations early next year with studios and nets.

AFTRA alleged that the Screen Actors Guild has breached the 26-year-old Phase I joint bargaining agreement between the unions by its move in July to institute “bloc voting” on its negotiating committee — meaning all votes by SAG reps on the panel would be counted as votes toward whatever their majority decided.

“There is no other conclusion than that SAG has unfortunately terminated the joint bargaining agreement,” said AFTRA president Roberta Reardon in a statement.

When asked about Monday’s announcement, AFTRA spokesman John Hinrichs agreed that a possible outcome could include SAG and AFTRA negotiating separately on the film-TV pact.

But SAG national exec director Doug Allen said AFTRA’s reached the wrong conclusion.

“AFTRA’s press release today is simply wrong. I have communicated clearly to (AFTRA exec director) Kim Roberts Hedgpeth, and the AFTRA leadership, that Screen Actors Guild remains committed to joint bargaining under the Phase I agreement. Any assertion that Screen Actors Guild has violated Phase I is completely inaccurate.”

SAG’s leaders opted for bloc voting after failing to persuade AFTRA to allocate more seats at the bargaining table to SAG, based on the notion that guild members generate the lion’s share of work. The “bloc voting” idea had been opposed not just by AFTRA but by SAG moderates out of concerns that those in power at SAG tend to espouse a far more aggressive stance than those at AFTRA.

AFTRA’s national board voted Saturday to “strongly urge” the SAG board rescind the action.

“The interests of performers must be the No. 1 priority of our unions, and the upcoming negotiations must be our main focus,” said Reardon. “The time is long past for SAG to affirm the letter and spirit of Phase I, and reverse its decision to institute ‘bloc voting,’ a decision which effectively terminates the Phase I agreement.”

The performers unions have been at odds for many years over jurisdictional issues, but the relationship has turned especially sour in recent months. SAG took the issue to its 120,000 members last week via its quarterly magazine, accusing AFTRA of poaching SAG’s turf on basic cable shows and shilling for producers by signing lowball deals.

SAG’s attack — which came in the form of a 12-page letter to members from Doug Allen — pointed out that the performer pay under the new AFTRA contracts is as much as 53% lower than under SAG pacts.

Reardon responded to the article by accusing SAG of trying to take over AFTRA.