Mobile phone carrier KDDI Corp. and convenience store operator Lawson Inc. will tie up on smartphone payments and combine their customer loyalty point programs to strengthen competitiveness against rivals, the two companies announced Monday.

KDDI, which operates the au Wallet point service for its customers, will buy 2.1 percent of Lawson shares and take a 20 percent stake in the company running Lawson's Ponta point program, the companies said.

The two firms' point programs will be integrated into Lawson's Ponta program in May, they said.