Around 40 climate activists have staged a peaceful occupation of the Scottish parliament’s debating chamber, urging MSPs to introduce much tougher climate targets.

Campaigners with the recently formed direct action group Extinction Rebellion posed as tourists on a visit to Holyrood before staging an hour-long sit-in in the chamber.

There were no arrests. Police escorted the protesters from the building through a side entrance and they were greeted by cheers from other campaigners gathered outside the parliament.

Extinction Rebellion was launched last October with the backing of 100 academics and the former archbishop of Canterbury Rowan Williams. Friday’s occupation was the group’s first direct action in Scotland, after sit-down protests in Parliament Square, Westminster, and at climate talks in Poland.

Robert Alcock, a builder and eco-designer who took part in the sit-in, said the group wanted Holyrood to take up far more ambitious CO2 reduction policies geared towards cutting net emissions to zero by 2025, in line with analysis from the International Panel on Climate Change.

Extinction Rebellion wants Scotland to convene a citizens’ assembly to decide how to achieve that goal through consensus. It would be made up of 73 members of the public drawn from Holyrood’s 73 single-member constituencies, and have the power to revise the parliament’s climate bills.

The Scottish government insists the country’s climate policies, enacted by Holyrood, are among the most ambitious and far-reaching in the world, and the most radical from any UK legislature.

Scotland’s first target to reduce CO2 emissions by 42% by 2020 has already been met, and the parties are now debating a fresh target to hit 90% by 2050 in a new climate bill.

Asked why Extinction Rebellion was targeting Holyrood rather than oil companies in Aberdeen or the oil refinery at Grangemouth west of Edinburgh, Alcock said: “This is a very symbolic place because it is representing the people of Scotland, and today is Burns Day, the day of Scotland’s national poet.

“While it is relatively progressive compared to other countries it comes nowhere near what is necessary to really address the gravity of the climate emergency.”

A Scottish parliament spokeswoman said: “Around 40 individuals on a free public tour refused to leave the chamber for approximately 60 minutes before leaving peacefully at 1.30pm.

“The public tour route takes in the debating chamber when parliament is not sitting. There was no impact on parliamentary business.”