The election campaign office of Japanese lawmaker Anri Kawai, wife of former Justice Minister Katsuyuki Kawai, is suspected of covering up illegally large payments to staff members during last year's upper house election, sources close to the matter said Thursday.

The office of Anri, 46, who won a seat for the Liberal Democratic Party in last July's House of Councillors election, allegedly split payments of double the permitted amount over two receipts to conceal the offense.

The daily allowance payments totaling 30,000 yen ($273) were made to a group of "election warblers," as women who are driven around in small vans touting their candidates over loudspeakers are known.

The campaign staffers were paid double the legal allowance, according to the sources. The payments may be considered bribery of campaign members, in violation of Japan's election law.

(Photo shows copies of the receipts.)

Investigators suspect the campaign office made separate receipts to be signed by the campaign workers to make it appear the payments were under the legal cap of 15,000 yen per day, they said.

Securing skilled campaign staffers for the election was a top priority for the LDP, which sought to hold both seats up for grabs in the closely-contested constituency of Hiroshima for the first time in 21 years.

Prosecutors are investigating whether LDP member Katsuyuki, who was actively recruiting the campaign staffers, was involved in deciding the payment amounts.

He had asked people around him whether they knew of any good "election warblers" following the LDP's approval of Anri as the second candidate in March last year, the sources said.

On Wednesday, prosecutors searched the offices of Katsuyuki, 56, and Anri as well as the home of one of the latter's secretaries over the alleged violations.

(Combined photo shows Anri Kawai (L) and Katsuyuki Kawai.)

Investigators will look into who instructed the payments to be made via separate receipts, the sources said.

Some of the campaign staffers have admitted to receiving the 30,000 yen allowance under voluntarily questioning by prosecutors, according to the sources.

The two kinds of receipts were titled "reward for election warblers" and "labor cost." Anri's office attached only the former to a report on income and expenditure during the campaign submitted to Hiroshima Prefecture's election board.

Kawai resigned as justice minister in October after the Shukan Bunshun weekly magazine reported the allegation, while his wife submitted to the LDP a medical certificate stating she was diagnosed with an adjustment disorder and needs to rest for one month.

Both have denied any intention to resign either as lawmakers or as LDP members even after Wednesday's search.

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