Japan Post Holdings Co. says it will look into 220,000 more insurance contracts — signed by around 60,000 customers — that are suspected of being part of a widening scandal involving improper sales.

In an announcement Friday, the former state-owned postal group also said that as of Wednesday, 106 legal violations and 1,306 breaches of in-house rules had been found among the roughly 183,000 insurance contracts already being investigated.

The number of problematic contracts has more than doubled from the 670 confirmed by Dec. 15. In the latest cases, the postal group said some customers ended up paying high fees after being advised to purchase multiple policies or encouraged to repeatedly conclude and cancel policies.

The fraudulent sales by the postal group shocked the public, especially people living in rural areas, who are more reliant on services offered at post offices.

The ongoing probe has found that over 70 percent of the customers who were improperly sold policies were age 60 or above, and that one of the root causes was that salespeople were focused on achieving quotas or earning additional bonuses by selling multiple policies.

The Financial Services Agency late last year ordered two units of the group, Japan Post Insurance Co. and Japan Post Co., to suspend new sales of insurance products for three months from Jan. 1.

On Friday, new Japan Post Holdings President Hiroya Masuda, a former internal affairs minister, said at a news conference that the group was still unsure when sales would resume.

"We're eager to resolve the disadvantage for customers as quickly as possible, and regain their trust step by step," Masuda said.

Former Japan Post Holdings President Masatsugu Nagato and the presidents of the two subsidiaries resigned on Jan. 5 to take responsibility for the scandal.