TOKYO, June 22 (Kyodo) — Japan's convenience store sales in May rose 1 percent from a year earlier to 620.35 billion yen on a same-store basis, an increase for the 13th consecutive month, due partly to continuing strength in cigarette sales, an industry body said Monday.

The number of visitors to convenience stores was up 2.5 percent to 1.09 billion, an increase for the 14th straight month, but purchases per person were worth 570.6 yen, down 1.5 percent, falling for the sixth month in a row, according to the Japan Franchise Association.

Tobacco sales have grown ever since Taspo smart cards, designed to prevent minors from buying cigarettes from vending machines, were introduced last July. Many smokers without the age-identification cards continued buying cigarettes at convenience stores instead of using vending machines.

Another item that sold well was protective masks to guard against a new influenza that spread worldwide, the association said.

The survey covered outlets operated by 11 major convenience store companies that belong to the association.