By Luciana Magalhaes and Ana Mano

SAO PAULO (Reuters) -An early count of JBS shareholder votes released on Thursday showed a slim majority opposed to the Brazilian meatpacker's proposal to list shares in the United States, threatening a move that has driven a sharp rally for its shares.

In a securities filing, the company released a voting bulletin showing about 52% of votes so far opposed the plan.

The preliminary count underscored that the issue is going down to the wire at a Friday shareholder meeting that will tabulate outstanding votes by minority shareholders.

JBS shares, which have surged over 30% since mid-March as stock analysts touted the advantages of a U.S. listing for its valuation, rose an additional 1% in Thursday morning trade.

People familiar with the operations said many investors have been buying additional shares to influence the final vote.

Plans for a U.S. listing were delayed repeatedly over the past decade, hindered by scandals involving the company's top shareholders, brothers Joesley and Wesley Batista, as well as concerns about its environmental impacts and the transparency of its climate targets.

Since the Securities and Exchange Commission gave its greenlight for the New York listing in late April, environmental groups and U.S. politicians have aired their concerns.

Thursday's filing showed some 271 million votes against the proposal to delist shares from the Sao Paulo stock exchange in order to create a dual U.S.-Brazil listing via a Netherlands-based entity. The question had 246 million votes in favor and over 3 million abstentions.

At a shareholder meeting on Friday, JBS is expecting to tabulate up to 210 million more minority shareholder votes, according to a person familiar with the process, who said those votes could swing the result in favor of the company's plan.

If approved, JBS shares will trade on the New York Stock Exchange as well as the Sao Paulo Stock Exchange (B3) via Brazilian Depositary Receipts (BDRs).

Recent recommendations by proxy advisory firms Glass Lewis and Institutional Shareholder Services cast fresh doubt on the proposal. Both questioned the structure of the listing, warning it could end up weakening minority shareholder rights.

Under the proposed structure, a Netherlands-based company will issue Class A shares, which will be publicly traded, and Class B shares, which will have 10 times as much voting power.

In one potential scenario, the controlling shareholders of JBS could end up with 85% of voting power.

JBS defended the proposed structure, telling shareholders in a letter that ISS had failed to recognize the strategic value of the controlling shareholders in achieving a leading position in the global meat industry.

(Reporting by Luciana Magalhães and Ana ManoAdditional reporting by Isabel TelesEditing by Brad Haynes)