Japanese Prime Minister Shinzo Abe, his popularity plunging amid a cronyism scandal, took responsibility yesterday for a loss of trust in his government but denied he or his wife had intervened in a land sale to a school operator with ties to his wife.

The finance ministry's announcement last week that documents about the discounted sale to educational body Moritomo Gakuen had been altered have sparked a political crisis for Abe, as suspicions swirl about a cover-up and opposition parties call for both the premier and Finance Minister Taro Aso to resign.

Interrogated by a parliamentary panel yesterday, Abe denied directing changes to the documents, in which references to Abe, his wife and Aso were removed from the finance ministry's records of the land sale. He told the panel he had not even known of the documents' existence.

"I did not direct that the documents be altered," he said.

"In fact, I didn't even know that they existed at all, so how could I have done that?"

Two opinion polls published over the weekend showed Abe's support diving to its lowest since he took office in December 2012, and others showed a majority of Japanese believed he bore some responsibility for the scandal.