PepsiCo (PEP) engaged in some saber rattling against its largest bottler, filing a lawsuit against Pepsi Bottling Group Inc. (PBG) that claims the bottler intentionally failed to give notice of a recent board meeting to its directors affiliated with Pepsi.

The move comes a week after Pepsi Bottling rejected a nearly $4.2 billion offer from PepsiCo to buy the remaining two-thirds stake it doesn't already own of the bottler, calling the bid inadequate.

PepsiCo owns about 33% of the bottler. Two senior PepsiCo executives, John Compton and Cynthia Trudell, are on the bottler's board. The lawsuit is the latest wrinkle in the proposed deal, but investors seemed to be counting on the acquisition ultimately going through. Shares of Pepsi Bottling were recently flat around $32, above the implied $29.50 cash and stock offer price from PepsiCo. Shares of Pepsi Americas (PAS), the other bottler that PepsiCo made a bid for, also showed little reaction to news of the lawsuit against the bigger bottler.

PepsiCo alleged Monday that some of the bottler board's actions - including the adoption of a shareholder rights plan - at a meeting are invalid because the full board wasn't present. Shareholder rights plans, or poison pills, are often put in place to prevent coercive takeovers.

"PepsiCo has filed a lawsuit that is entirely without merit in an attempt to divert attention from its grossly inadequate proposal," said Pepsi Bottling spokesman Jeff Dahncke via email.

Morton Pierce, chairman of law firm Dewey & LeBoeuf's mergers and acquisitions group, said the procedure might be fairly easy to remedy even if the bottler had failed to give notice of the meeting to the directors affiliated with PepsiCo. With just two directors on the bottler's board, PepsiCo doesn't have a majority. Pierce, who isn't connected with the deal, said that the rest of the board would likely be able to allow the poison pill to go ahead. If needed, he said, the bottler may be able to call another meeting, give notice to all directors and adopt the poison pill again.

Still, the lawsuit highlights the challenges that PepsiCo faces in negotiating with its bottlers. If the talks get too fractious, the company runs the risk of damaging its relationship with its bottlers, who are essential to the distribution of its beverages.

"We believe it is important from PepsiCo's perspective to close a deal sooner rather than later, to minimize bad feelings on either side or system disruption, and to avoid a public squabble," wrote Deutsche Bank analyst Marc Greenberg in a recent research brief to investors.

PepsiCo declined to comment beyond its publicly issued press release.

PepsiAmericas has also rejected PepsiCo's bid, calling it inadequate. The bottlers' refusals have been viewed as more of a negotiating tactic than an outright renunciation of the deal. The companies have both been widely expected to negotiate for a higher offer.

-By Anjali Cordeiro; Dow Jones Newswires; 201-938-2408; anjali.cordeiro@dowjones.com

-By Lauren Pollock, Dow Jones Newswires; 201-938-5964; lauren.pollock@dowjones.com