The Scottish Parliament is taking legal advice about what to do about a group camping outside Holyrood calling for a second independence referendum.
The People's Voice group say they plan to keep their IndyCamp Live campaign going until Scotland is independent.
A letter from Scottish Parliament clerk and chief executive Paul Grice to MSPs said the campers did not have permission to occupy Parliament land.
He said legal advice was being sought and the situation being monitored.
Organisers said the IndyCamp Live project was a "continuation" of the five-year Democracy for Scotland vigil, which campaigned for devolution in the 1990s.
They plan to keep the camp constantly manned until Scotland is independent from the UK, saying they are prepared to stay "however long it takes".
However, Mr Grice said camping on the Parliamentary estate was not permitted, and said the protestors had "declined to consider alternative options".
In a letter to members, he said: "The protestors have indicated they plan to camp indefinitely on Parliament land without permission.
"As a Parliament we recognise the importance of peaceful protests in a democratic society and regularly accommodate demonstrations outside the Parliament.
"However, in seeking to occupy this land on a long term basis the protestors are preventing others from using this public space. Their prolonged presence could also act as a draw for others with the same, or differing, views, thus exacerbating the situation.
"We are monitoring the situation and taking legal advice on the avenues open to the Corporate Body to return this area to public use."
Mr Grice said the protestors had "refused further direct contact with Parliament staff", but said the Parliament would continue to work with them through police liaison officers.