Japan's finance ministry has called on X, formerly known as Twitter, to take down an account impersonating its top currency diplomat Masato Kanda.
"Please don't follow the impersonation account and/or comment on the post," the ministry said in a rare post in English on the social media platform.
Mr Kanda is a key figure in efforts by the world's third largest economy to stabilise the value of the yen.
The fake account now appears to have been suspended.
X, which is owned by the multi-billionaire Elon Musk, did not immediately respond to a BBC request for comment.
Mr Kanda is an influential voice amongst Japan's monetary policy makers. His public comments have the potential to move the yen's value against other major currencies.
The account, which was followed by around 550 users, had not made comments on the yen or financial markets, according to the Reuters news agency.
There had been five posts on the account, with the most recent appearing to impersonate Mr Kanda's trip to Ukraine earlier this week, the agency reported.
"A Twitter impersonation account (Masato Kanda @Jgghkj_) posing as Vice Minister Kanda Masato of the Ministry of Finance of Japan was confirmed," the ministry said in a post on X on Thursday.
The ministry added that it was "currently requesting that X (formerly Twitter) suspends the impersonation account."
On Friday, a notice on X showed that the account had been suspended for violating "Twitter Rules".
The yen has long been seen as a safe haven in the global financial markets, which investors traditionally bought at times of crisis.
However, the currency has fallen in value against the US dollar in recent months. This is because Japan's central bank has kept its main interest rate below zero, even as central banks around the world raised their interest rates sharply.
Higher interest rates tend to make a currency more attractive to investors.
As a result there is less demand for currencies from countries with lower rates and those currencies fall in value.
Last week, the Bank of Japan kept interest rates at ultra-low levels but said it would allow rates to rise more freely.
However, the yen weakened to hit 143.89 against the dollar on Thursday, its lowest level in over a month.