A 26-year-old was tonight released with a police caution after he had earlier climbed onto a balcony at the Irish Embassy in London.
The man, who was protesting against a controversial Shell gas pipeline in north Co Mayo, initially refused to leave but was eventually talked down by police.
A Scotland Yard spokesman said tonight: “Following an incident at the Irish Embassy today, a 26-year-old male was questioned under Section 9 of the Criminal Law Act, 1977, for trespassing on a diplomatic premises.
“Following questioning, he was released with a caution.”
Scotland Yard confirmed no criminal damage to the Embassy, located in Grosvenor Place, was recorded.
It is believed that the protester was a British national and had an address in Sheffield.
Up to 10 members of a group that called themselves the ’Rossport Solidarity Camp’ handed out leaflets to passers-by during the hour-long incident which began at noon.
The Foreign Affairs Department in Dublin earlier confirmed a man climbed on to the external balcony of the ambassador’s office at the Irish Embassy.
“He unfurled a banner with the words ’Shell To Sea’ written on it. He refused requests to leave by Embassy staff. The police were called who then talked him down.
“He exited through the Embassy building shortly after 1pm. He was arrested by police,” a spokesman said.
Protesters have waged a two-year campaign against a high-pressure gas pipeline being built by Shell in Rossport in Co Mayo.
They want Shell Ireland to build its terminal in the sea rather than inland near their homes.
Five local residents known as ’the Rossport Five’ were jailed for 96 days by the Irish High Court in 2005 for blocking work on the project.
The Irish Embassy was the scene of another protest in March 2005 when British anti-war activists picketed the building over the refuelling of US military aircraft at Shannon Airport.