According to the ministry, Viinanen acted contrary to the duties of his office while managing the embassy, and did behave or perform his tasks improperly as required by the embassy.
The warning is based on, among other things, written reports of people who worked alongside Viinanen as well as an internal audit memo.
The embassy underwent an audit in the spring, which focused on well-being and leadership.
Viinanen was recalled from Stockholm back to Helsinki in September because the internal audit revealed that he had behaved inappropriately in his duties.
According to publicly released information, Viinanen is suspected of sexual harassment.
He had denied all allegations.
