A protester is in critical condition after setting themselves on fire outside an Israeli consulate in the United States in what police said was an “extreme act of political protest”.

Officials said a Palestinian flag was recovered from the scene of the blaze which occurred just after midday Friday outside the Consulate General of Israel in Atlanta.

Atlanta police Chief Darin Schierbaum said the unidentified protester, who had used petrol as an accelerant, suffered “100 per cent burns”.

A security guard who tried to intervene suffered burns to the wrist and leg. He was also taken to hospital. 

Mr Schierbaum said there was no evidence the person’s actions were part of a broader terror plot and police did not believe there was a specific threat to the diplomats working in the building.

“We do not believe there’s any nexus to terrorism at this location. We do believe, based on the evidence that is readily available for us, this was likely an extreme act of political protest that occurred here,” he added.

Mr Schierbaum said his department had spoken to federal officials in the Department of Homeland Security, and their state counterparts in Georgia. The FBI was also involved in the investigation. 

Special units of officers had been set up to patrol the city’s various Jewish and Muslim neighbourhoods as conflict in Israel and Gaza has continued for two months, Mr Schierbaum said.

Anat Sultan-Dadon, Consul General of Israel to the Southeastern United States, said Friday “it is tragic to see the hate and incitement toward Israel expressed in such a horrific way”.

“We are saddened to learn of the self-immolation at the entrance to the office building,” Mr Sultan-Dadon said.

’’The sanctity of life is our highest value. Our prayers are with the security officer who was injured while trying to prevent this tragic act. We are grateful to the city of Atlanta’s law enforcement and first responders for all they do to ensure safety.”

Officials said the protester had been taken to the city’s Grady Memorial Hospital.