Activist investor Nelson Peltz' battle for a Procter & Gamble board seat was suddenly revived Wednesday after an updated shareholder vote count showed the billionaire had inched ahead of a company-backed nominee.

P&G had claimed a narrow victory in a vote at the October 10 annual meeting, but a preliminary recount overseen by independent elections supervisor IVS Associates showed Peltz with a slight edge, both sides said Wednesday. 

P&G shares jumped on the development, rising 2.8 percent in after-hours trading to $90.70. The costly months-long battle pitted the maker of Gillette razors and Olay soap against a hedge fund chief who has pitched himself as the outsider needed to reignite P&G.

Citing the latest tally, Peltz' firm, Trian Fund Management, called on the consumer products giant to "accept the Inspector's tabulation and not waste further time and shareholder money contesting the outcome of the Annual Meeting."

"Shareholders have voted, and they have indicated that they want Nelson Peltz to join the Board," Trian said in a statement.

But P&G signaled it would not back down, saying the vote tally is razor thin and not final.

Peltz leads P&G nominee Ernesto Zedillo "by a margin of approximately 0.0016% of shares outstanding or approximately 42,780 shares," P&G said. 

"The results are still preliminary and are subject to a review and challenge period during which both parties will have the opportunity to review the results for any discrepancies," the company added.

Peltz has attributed the company's declining market share in key businesses and sluggish sales to P&G's "slow moving and insular culture." But P&G argued that it was on the right track with its own reform plan and that Peltz' election would disrupt its progress