An investment vehicle controlled by China National Chemical Corp (ChemChina) said it will launch a mandatory tender offer for remaining shares in Pirelli after taking control of the Italian tyremaker through a deal struck in March.

ChemChina in March agreed to become the majority owner of the world's fifth-largest tyre manufacturer as part of a 7.3 billion euro ($8 billion) deal.

Marco Polo Industrial Holding, a company created to facilitate the Chinese takeover, concluded its acquisition of a stake in Pirelli from Italian holding company Camfin, triggering the mandatory takeover bid.

A Camfin spokeswoman said the tender offer was expected to be launched in September.

State-owned ChemChina holds a 65 percent stake in Marco Polo, with the remainder in the hands of Camfin investors, who include Pirelli boss Marco Tronchetti Provera, Italian banks UniCredit and Intesa Sanpaolo, and Russia's Rosneft.

The tender offer will be launched at 15 euros per share with the goal to acquire all of Pirelli's share capital and de-list the tyremaker from Milan's stock exchange. Marco Polo also decided to launch a voluntary tender offer on Pirelli's savings shares.

In a separate statement, Tronchetti Provera, who will remain Pirelli's chief executive, said Camfin would invest more than 1 billion euros in the tender offer and will keep a central role in the tyremaker's future shareholder structure, along with ChemChina.

He reiterated the Chinese investment would boost the company's international growth, particularly in the industrial tyre sector.

"In this segment, the integration with ChemChina will allow immediate growth in volumes and market share that Pirelli alone would have taken years to achieve," he said.