Prime Minister Shinzo Abe, who turned 61 on Monday, received a birthday surprise of sorts via Twitter the same day, when his account replied to felicitations from Indian Prime Minister Narendra Modi.

Or so he thought.

Instead of sending the message to Modi's account, @narendramodi, Abe's account added a space between the Indian leader's first name and surname, mistakenly replying to a different person's account, @narendra.

"Thank you, my friend @Narendra Modi, for birthday wishes. I also cherish our interactions. I look forward to seeing you soon," Abe's account tweeted.

Noticing Abe's mistake, the @narendra account holder, whose profile says he is a California-based Web entrepreneur, responded wryly.

"PM of Japan doesn't have mastery of at reply..." he tweeted.

Abe's account quickly deleted the tweet and posted a corrected version.

Abe, who is often too busy to tweet messages with a PC or smartphone himself, has been known to have aides and others do it for him.

Liberal Democratic Party lawmaker Ichita Yamamoto, who is close to Abe, revealed in May that he had been writing Abe's messages and uploading them, when he mistakenly posted a personal tweet with Abe's account.

At the time, Yamamoto said that Abe had asked him to tweet in his stead, but that the messages are all dictated by the prime minister.

Whether Abe himself or an aide sent the latest message is unclear.