Matsuo: Sacked earlier this year for corruption

They also hired taxis in the capital Tokyo for officials working on the summit preparations.

The arrested diplomats are Hiromu Kobayashi, 45, an assistant director at the ministry's economic affairs bureau, and his 38-year-old subordinate Tsutomu Okuma, a police spokesman said.

Correspondents in Tokyo say this is the latest of a series of scandals to hit the foreign ministry, and will only increase local perceptions that it is riddled with corruption.

Extra cars

The two men are accused of instructing the car-hire company to over-bill the government for vehicles used between January and June last year, the reports said.

Government officials used only one car, but were billed by the car-hire company for four, the newspapers said.

In return, the company gave Mr Kobayashi and Mr Okuma the taxi and highway toll coupons, which can be exchanged for cash at special shops, the reports said.

Kyodo and Asahi said the two suspects cashed in about 10 million yen of the coupons, and further tickets worth two million yen were found in Mr Kobayashi's home.

Scandal

Another former diplomat was arrested earlier this year and accused of siphoning off millions of dollars worth of public funds to finance a jet-set lifestyle.

Matsuo: Sacked earlier this year for corruption

Katsutoshi Matsuo, 55, was arrested in March for allegedly siphoning off 420 million yen from a fund for official foreign trips.

Domestic media said he bought more than a dozen racehorses, as well as golf club memberships and a luxury apartment in Tokyo.

Foreign Minister Makiko Tanaka has vowed to punish those responsible for that scandal, and has accused ministry officials of dragging their feet in the investigation.