Mitsui Sumitomo Insurance Co. is expanding its partnership with Malaysian billionaire Quek Leng Chan's Hong Leong Financial Group Bhd. by acquiring a 35 percent stake in its Islamic insurance unit.

The Tokyo-based company, a unit of Japan's biggest casualty insurer, MS&AD Insurance Group Holdings Inc., bought the interest in Hong Leong MSIG Takaful Bhd. for 33.6 million ringgit ($11 million), according to a joint company statement. The stake was previously held by Tokio Marine Holdings Inc., which decided to exit the joint venture, Raymond Choong, Hong Leong Financial's chief executive officer, told reporters in Kuala Lumpur.