Japan's chief negotiator in the controversial Trans-Pacific Partnership (TPP) trade deal has been accused of taking bribes worth $100,000 from a construction company.

Economy minister Akira Amari and his staff accepted 12 million yen ($101,000) in payments from an unnamed company from the Chiba province just outside Tokyo, according to hard-hitting weekly magazine Shukan Bunshun.

The magazine quotes an anonymous executive at the company in question who claims he had taken the minister and two members of his staff out to dinner repeatedly and given them "thank you gifts" of envelopes containing 500,000 yen ($4,200) in cash.

He also claims to have personally handed Amari one million yen and to have recordings of meetings, copies of receipts, and a log of payments made.

The magazine said it was unable to find any description matching the payments in Amari's political fund.

The report has already caused political ructions with opposition politicians questioning the minister in the Japanese parliament about it. Adding fuel to the fire, Amari admitted he has met executives from the construction company but couldn't remember the details. He promised to investigate the report.

Although the payments were not related to the trade deal – they were seemingly over an unrelated road construction project – the allegations have created problems for it. Amari was the chief negotiator for Japan, and Japan played a key role in deciding the final language.

The deal is due to be formally signed next month in New Zealand but the Liberal Democratic Party needs the support of other parties to formally ratify it.

The TPP is a huge trade agreement and pulls 12 countries on the Pacific Rim into what would be the world's largest free-trade area. As well as Japan, its signatories include the United States, Australia and Canada.

Although there are likely to be significant benefits to the agreement, it contains a number of technology aspects that people are concerned about – including weak privacy protections, restrictions on localizing data, and a ban on restricting data transfer. While that may be good news for the digital economy, critics say it would enable the NSA and US government to continue mass surveillance across the internet. ®