Prime Minister Shinzo Abe's approval rating has taken a hit in the past month, a media poll has shown, as accusations grow that his office may have violated political spending laws.

Allegations that the prime minister's private political office sponsored a party for supporters are the latest in a string of gift-giving scandals that have put politicians' positions in question across Japan in recent months and eroded public sentiment.

A monthly poll by the daily Yomiuri Shimbun conducted late last week showed an approval rating of 49 percent for Abe's Cabinet, down 6 points from the results of its October poll, and falling below 50 percent for the first time since February.