An online drugstore was found to have offered for sale in late July through a shopping mall of Yahoo Japan Corp. non-prescription medicines that had passed their expiry dates, and at below market prices, sources familiar with the matter said Thursday.

This is the first case of its kind, and came to light as online sales of non-prescription medicines is gaining momentum in the absence of regulations to ensure the safety of drugs sold online.

Yahoo Japan said it deleted mall pages offering the drugs on the grounds the marketing violated company guidelines for appropriate sales practices.

The incident has also led the Ministry of Health, Labor and Welfare to consider including a ban on the sale of out-of-date medicines in new rules for online drug sales.

Although Japan does not have any law banning sales of out-of-date medicines, such drugs are usually not sold at drug stores operated by licensed pharmacists.

The online drugstore was selling several types of non-prescription drugs at below market prices by saying that they "have passed their expiry dates," Yahoo Japan said without identifying the drugs.

Yahoo Japan said it is now seeking to determine what quantity of medicines were sold.

In January, the Supreme Court ruled that an ordinance issued by the ministry that uniformly banned online sales of certain categories of drugs was "illegal and invalid."

Following the top court ruling, the government in mid-June began allowing more than 99 percent of non-prescription drugs to be sold in Japan via the Internet.