The Scottish Parliament is taking legal action to evict nationalists illegally camping on its grounds.

The People's Voice camp was given 48 hours to leave on Tuesday after a growing number of pro-independence activists brought caravans, fuelled generators and started lighting fires.

The group has refused to leave unless Scotland is granted a second independence referendum, but Holyrood bosses say the group's partisan message is at odds with the parliament's "politically-neutral position".

A Scottish Parliament spokesman said: "We note that the period given to the campers to remove has passed without them complying with our request. Accordingly, as we stated in our letter, we are raising court proceedings for recovery of possession and we have arrangements in hand."

In a letter to MSPs on Tuesday, Scottish Parliament chief executive Paul Grice said: "Over the last week we have seen a gradual increase in the size and scale of the camp with the arrival of a caravan, cars and the use of petrol/diesel generators, lighting and fire braziers.

"The protesters have made it clear that they intend to camp indefinitely on Parliament land without permission and will not consider alternative options such as the organisation of a series of one-day protests outside the building.

"There are many ways groups and individuals can engage with the Parliament and make their views known.

"However, the occupation of a public space on an exclusive basis and to the exclusion of others is not a precedent that the corporate body wishes to see established.

"In addition, the presence of a permanent camp advocating a particular position is at odds with our policy on the use of parliamentary resources under which we aim to maintain a politically-neutral position.

"While our strong preference was to resolve the issue through mutual agreement, it is clear that we must consider alternative routes to return this land to public use.

"We have been in discussions with our legal advisers and now believe we have sufficient grounds to pursue a legal remedy to the situation."