* Shares remain halted till delisting in September
* PAG now holds 98.1 pct of the firm
* Says only 1.89 pct in public hand, unable to meet requirement (Adds details on Yingde Gases boardroom battle, takeover approaches)
HONG KONG, May 5 (Reuters) - The Hong Kong stock exchange halted trading of Yingde Gases' shares on Friday, as private equity firm PAG consolidates its grip on the stock ahead of a planned delisting in coming months.
China's largest producer of industrial gases was the subject of a rare public Chinese boardroom battle that pitted one of its co-founders against two other co-founders, paving the way for four separate takeover approaches from companies including PAG and Air Products and Chemicals Inc.
PAG finally won out when Air Products dropped its $1.5 billion bid in March, saying the deal wasn't in the best interest of its shareholders.
Hong Kong-based PAG agreed to buy the 42.1 percent stake of the three co-founders of Yingde Gases for $616 million. PAG later became the company's controlling shareholder when it made a compulsory offer for all outstanding shares it did not already own.
PAG owned 98.1 percent of Yingde Gases as of May 4, when it closed the buyout offer and requested for a trading halt, according to a statement to the Hong Kong stock exchange late on Thursday.
With just 1.89 percent of the company's issued share capital held by the public, Yingde Gases said it was unable to fulfil its minimum public float requirement under stock exchange rules and asked for the shares to remain halted until the listing is withdrawn.
Yingde Gases, which went public in October 2009, expects to complete its delisting in September. Its shares slumped in 2015, weighed down by concerns of a slowdown in China's economy and massive output cuts in the steel, iron ore and chemicals industry.
The stock tumbled further, reaching their lowest level in 2016, before Air Products sent a "letter of interest" to Yingde's board in December. Shares have since more than doubled in price.
Yingde's main products include oxygen, nitrogen, argon and some speciality gases, which it sells primarily to companies in the steel, iron ore, chemicals and electronics industries. (Reporting By Donny Kwok and Twinnie Siu; Writing and additional reporting by Elzio Barreto; Editing by Sherry Jacob-Phillips and Randy Fabi)