Japan's Ministry of Finance (MOF) warned on Thursday of a fake account for its top currency diplomat Masato Kanda on social media X, formerly known as Twitter, as the market fears a currency intervention amid the yen's drop to a one-month-low.

In a rare English-language post on X, the ministry said "Please don't follow the impersonation account and/or comment on the post", saying such an X account purportedly belonging to Kanda or his staff did not exist.

"MOF is currently requesting that X (formerly Twitter) suspends the impersonation account. Thank you for your cooperation" it said, in its official account. The social media platform suspended the fake account within hours.

This time, a Twitter impersonation account (Masato Kanda @Jgghkj_) posing as Vice Minister Kanda Masato of the Ministry of Finance of Japan was confirmed. Twitter account owned by himself and his staff does not exist.

— 財務省 (@MOF_Japan) August 3, 2023

The account, under the name "Masato Kanda" and the user ID "@Jgghkj_", appeared to have been created in March and made only five posts to date, including three pictures of Kanda posted on March 1. The latest post, made at 3:56 pm (0656 GMT), appeared to have impersonated Kanda's recent trip to Ukraine.

Kanda was in Ukraine on Wednesday to explain Japan's support for the country, the MOF had announced.

The fake account, which was following about 5,000 users and was followed by little more than 550, had made no remarks about the yen or financial markets.

Kanda, Japan's vice-minister of finance for international affairs, has been the central figure in the country's efforts to stem the sharp decline of its yen currency since last year, supervising record yen-buying, dollar-selling operations late last year.

Prior to the Bank of Japan's latest July 27-28 policy meeting, Kanda, in an unusual move, referred to market speculation about a possible tweak to monetary policy, in addition to warning the market that authorities will consider all options to deal with the yen's excess volatility.

The BOJ surprised markets with a tweak to its bond yield control programme last week, allowing interest rates to rise more freely.

The yen weakened on Thursday to hit 143.89 against U.S. dollar, its lowest since July 7, as BOJ announced emergency bond purchases to check a surge in 10-year bond yields.

Markets are closely watching the MOF's next moves as the yen is nearing 145 per dollar again, a level that triggered Japan's first yen-buying intervention since 1998 last September.