TOKYO, April 14 (Xinhua) -- A man in his thirties was arrested here on suspicion of obstructing public service when participating in a massive rally against Japanese Prime Minister Shinzo Abe's administration Saturday afternoon, according to local reports.

Some 30,000 people participated in the rally in front of parliamentary buildings in Tokyo, protesting against the cronyism scandals implicating the prime minister and demanding Abe's cabinet to step down.

"Using public power for private use shall not be allowed!" "Abe shall step down!" Protesters, including students, young parents as well as senior citizens, shouted in front of the parliamentary buildings, holding banners and flags.

The man who was from the neighboring Saitama prefecture, allegedly pushed a police officer when being stopped from crossing a road fence. The man denied the allegation, according to local reports.

The massive protests on Saturday occurred following the revelation on Friday that a document related to one of the influence-peddling scandals implicating the prime minister had been found at a government ministry.

According to Agriculture, Forestry and Fisheries Minister Ken Saito, the document had been kept at the farm ministry. It allegedly showed that a secretary of Abe's at the time informed local officials that a project to open a veterinary school in Ehime Prefecture is a "matter concerning the prime minister."

Tadao Yanase, Abe's aide at the time, has denied making the comments and has said he does not remember such a meeting with the local officials, which was in contrast to the document's contents.

The meeting was held to discuss the opening of the school, the doors of which opened last week in western Japan by its operator Kake Educational Institution.

Abe has close ties with the school's operator, Kotaro Kake, and suspicions have long been circling that Abe used his influence in the government's approval of the newly-opened department at the Okayama University of Science.

Political observers on Friday said the latest revelation would provide further impetus for the opposition camp to insist the scandal is rectified by Abe and it could take a further toll on the public support rate for Abe's Cabinet and widen distrust in the current administration.

A survey released by Jiji Press on Friday showed that the Abe cabinet's support rate plunged to 38.4 percent, while the disapproval rate rose to 42.6 percent.