Douglas Carswell had to be escorted away in a police van after being confronted by anti-austerity protesters in London on Wednesday.
Ukip's only MP said he had "never seen such hatred" and had feared for his life after being surrounded by what he described as a "lynch mob" near Westminster.
Footage of the incident, where protesters can be heard chanting "Tory scum" and "racist", was captured by journalist Harry Cole who said he had "no doubt that crowd would have turned violent had the police not stepped in".
Carswell told the Press Association that he had been engaged in conversation with a smaller group of protesters before being surrounded by the larger mass.
If the police had not been there I do not think I would be here now. My safety was very, very seriously at risk. I have never seen such hatred. If this is the way the extreme left behave now, I do not think it bodes well for the future.
It is estimated that a few thousand people had gathered in Westminster to demonstrate against austerity measures being announced in the Queen's Speech.