TOKYO, March 19 (Xinhua) -- Japanese Prime Minister Shinzo Abe on Monday said he and his wife had no involvement in a cut-price land deal with a nationalist school operator or in more recent revelations of document-tampering related to the shady deal.

"I didn't know about even the existence of the Finance Ministry's internal settlement documents. I couldn't order the rewriting of them," Abe was quoted as saying in an upper house Budget Committee session on the contentious matter.

The leader of the ruling Liberal Democratic Party (LDP) also said that the deliberately altered records in question had led to growing mistrust in the government.

"The issue of rewriting the settlement documents has shaken public confidence in the government. I am seriously concerned," Abe told the committee.

The ongoing cronyism and document-tampering scandal have led to the approval rating for Abe's Cabinet tumbling by 9.4 percentage points from the previous poll conducted by Kyodo News, to 38.7 percent in a survey conducted over the weekend.

The protracted scandal implicating Abe, his wife and other senior ministers, sources said Monday, could seriously hurt Abe's chances of securing a third, three-year term as LDP President and in turn his chances of becoming Japan's longest-serving prime minister.

Abe has consistently denied he or his wife was involved in the scandal, vowing to step down as prime minister if the facts proved otherwise.