China's Bright Food Group Co Ltd said on Thursday it has signed a preliminary agreement to buy 56 percent of Israel's largest food company Tnuva from private equity firm Apax, extending a string of overseas acquisitions.

A spokesman for Bright Food did not disclose how much it has agreed to pay, but Israeli news websites reported late on Wednesday the deal valued all of Tnuva, a specialist dairy produce supplier, at 8.6 billion shekels ($2.5 billion).

When Apax and Israeli investment company Mivtach Shamir Holdings Ltd acquired control of Tnuva in 2008, the company was valued at $989 million in total.

"Israel is a country with highly developed agriculture and animal husbandry techniques. Tnuva, as Israel's largest food company, has a long history and various products and large market share," the Bright Food spokesman said in a text message sent to Reuters.

Shanghai-based Bright Food has not yet reached an agreement with Israeli investment company Mivtach Shamir Holdings Ltd, which owns 21 percent of Tnuva, the Calcalist website said. A group of kibbutzim, or cooperative farms, own the rest of Tnuva.

In January, Bright Food bought Australian dairy company Mundella Foods. It previously bought Australia's Manassen Foods, which supplies food brands to Australian retailers, and New Zealand's Synlait Milk Ltd.

Bright Food owns four mainland-listed companies including Shanghai Jinfeng Wine Co, Shanghai Haibo Co, Shanghai Maling Aquarius Co and Bright Dairy & Food Co.