The centre-left newspaper said that over the five years to 2012, her political funding body spent more than 10 million yen (HK$725,000) on things unconnected to politics, including cosmetics and accessories.

It also spent 3.62 million yen in a boutique run by her sister's husband, the report said, citing receipts it had obtained. Other reports claimed a separate Obuchi group had spent 26 million yen on theatre tickets for supporters.

Political funding rules in Japan do not explicitly bar much aside from outright bribery. They are generally interpreted to allow for spending on running offices and promoting individuals.

Rows about misspending are common, and usually provide little more than a sideshow in the very self-absorbed world of Tokyo politics, although they occasionally claim scalps.

Obuchi told a parliamentary committee that she was not personally involved in any of the spending in question.

However, "I believe this spending was necessary for my political activities", she said, while pledging to investigate claims of funding theatre tickets.

Obuchi is the second daughter of former prime minister Keizo Obuchi. She studied at Seijo University in Tokyo before joining the Tokyo Broadcasting System TV company in 1996. Two years later, she became her father's secretary.

Her rock solid political credentials mean she's unlikely to suffer any lasting damage from this make-up episode.

The 40-year-old was the highest profile woman among five to be named to the cabinet during a recent reshuffle. Her promotion was seen as part of an effort by Abe to bolster women, amid a campaign to increase their participation in the work force.