The UUP's health spokesperson has said she will write to the head of the Northern Ireland Civil Service over an email sent by a senior civil servant.
On Monday, it emerged that the Department of Health's permanent secretary emailed senior health chiefs.
Richard Pengelly expressed his concern about "overtly political tweets from colleagues across the service".
Jo-Anne Dobson said she would contact Sir Malcom McKibbin asking him whether his actions were "appropriate".
The BBC then obtained a different email sent to staff in the South Eastern Trust on Monday reminding staff to, "at all times remain publicly neutral in terms of expressing any political opinions for example, through social media".
Referring to Mr Pengelly's email, Mrs Dobson said she had spoken to "dozens of health workers about this issue".
"Setting aside the fact they are perplexed that the supposedly busiest permanent secretary in the country has time to monitor social media accounts, they are exasperated that of all the issues in the health service he should be focusing on at the moment, he decided this was one the most important.
"Richard Pengelly's intervention, only days before Northern Ireland goes to the polls, raises serious questions."
Mrs Dobson said she would ask if his intervention was "appropriate, especially in light of his relationship as the husband of a DUP candidate running in the current election and his presence at a counting centre last year, and if not what action will be taken against him."
The permanent secretary is married to outgoing DUP MLA Emma Little Pengelly.