The chief executive of a Melbourne non-profit organisation has expressed disappointment that an employee posted a fake job advertisement online to express dissatisfaction with her management style, rather than knocking on her door.

The fake advertisement for the chief executive's position was posted on seek.com.au over the weekend, saying the well-known organisation was in "desperate need" of a new CEO. The advertisement, which was removed from Seek a few hours after it was posted on Saturday, went on to list the attributes not wanted in a new CEO. The stinging and defamatory attack implied the current CEO was, among other things, sulky, self-centred, dishonourable and disrespectful of staff.

"Are you single-minded, arrogant and unable to keep your staff engaged?" read one part of the ad; "Then we don't want you!"

The chief executive, who has no plans to step aside from her role, told theage.com.au she was upset and disappointed by the prank and said an investigation was under way to identify the culprit.

"Obviously we are really concerned about it," she said. The chief executive said whoever posted the advertisement had access to the organisation's Seek account and password.

"There's three possibilities," she said. "It is a former staff member, a current staff member or someone who has given the password to someone outside the organisation."

Seek allows members to write their own advertisements. A spokesman from Seek said the company had no comment on security or screening provisions on the website.

The chief executive said she had spoken to all staff today and had received expressions of support from several board members after the existence of the advertisement was broadcast on radio 3AW.