The Green MSP Ross Greer is facing an ethics investigation after being accused of bringing parliament into disrepute by organising a blockade of the building.

A member of the public is understood to have lodged a complaint with the Ethical Standards Commissioner for Standards about the incident on Wednesday evening.

It followed the West of Scotland MSP leading a protest against a “reception for arms dealers” at Holyrood sponsored by former Scottish Tory leader Jackson Carlaw.

Mr Greer said earlier this week that it was “profoundly sad” that the ADS event would go ahead while arms dealers were sending weapons “to perpetrate a genocide in Gaza”.

He said: “At the same time as Westminster is debating a ceasefire the companies who have fuelled and profited from this awful war will be using Scotland’s Parliament for a reception."

After activists blocked the public entrance to the parliament on Wednesday evening, Mr Greer boasted the Greens had stood with the people of Gaza, not the arms dealers “profiting from their slaughter”.

In a video he posted on social media, Mr Greer used a megaphone to tell the crowd afterwards: “Thank you so much for what you’ve achieved tonight.”

Other social media footage showed protestors, some with Palestinian flags, jostling with police and parliament staff outside the building.

At the end of FMQs today, Tory MSP Stephen Kerr used a point of order to accuse Mr Greer of bringing the parliament into disrepute by his actions.

Although he did not identify Mr Greer by name, he said: “Last night, members of the public seeking to enter this Parliament were obstructed and intimidated. 

“And all of this was orchestrated and trumpeted by a member of this Parliament, a Scottish Green MSP. 

“This is surely unacceptable conduct for a member of the Scottish Parliament to seek to prevent members of the public entering their own Parliament.

“What actions will now be taken in the light of last night's events to secure safe access for the public to enter their Parliament at all times? 

“And what action will be taken against the member who I believe has brought disrepute to the Scottish Parliament? 

“Because not only did he plan and conduct the obstruction and the demonstration, but he claimed responsibility for it, he sought to shut down this Parliament. 

“Now we all believe in freedom of speech and the right to protest. 

“But the right of the people of Scotland to come safely and securely into their parliament and leave their parliament when they choose to do so must also be safeguarded.”

Presiding Officer Alison Johnstone, a former Green MSP, said she was not aware of all the circumstances but it was clear that “the security of all building users and our guests is absolutely paramount”.

She said: “I can confirm that I'm aware that there were extremely difficult circumstances last evening, and all our scheduled events were able to proceed and I'm certainly very grateful to our staff and to police colleagues who made that possible.

“I can assure all members that our procedures are very much kept under review and they are adjusted where that is appropriate.”

Responding through another point of order, a visibly angry Scottish Green co-leader Patrick Harvie told Ms Johnstone: “I trust, and I hope we can all trust that, in your consideration of these issues, you will give a high priority to the absolutely essential role that the right of peaceful protest plays in our democracy and in the life of our parliament.”

She replied: “I am absolutely sure that all members here assembled understand the importance of the right of protest, but also of the importance that we place on the rights of all building users and staff to do so securely and safely.”

In a statement later, Mr Greer said: "The truly shameful scene last night was the wine reception for the arms dealers whose weapons Israel is using to slaughter children. 

"People across Scotland will be appalled that MSPs from multiple parties were willing to host such an event during an ongoing genocide.

"Peaceful protest, including direct action, is critical to our democracy and as public representatives we will all be judged for a long time to come on the actions we took to contribute towards an end to this slaughter. 

"The Scottish Greens proudly stand with the Palestinian people and for a lasting peace."