Green Party leader Natalie Bennett joined protesters in Sheffield city centre in a demonstration against the Immigration Bill.
Campaigners are against proposed changes to the Bill, which they say could make life more dangerous for immigrants.
Ms Bennett said she attended the event outside Sheffield Town Hall to mark International Migrants Day.
She said: “I wanted to come somewhere around the country where there’s a strong support for migrants.
“I know there’s a strong community here supporting them.”
Victor Mujakachi, who came to Pitsmoor as an asylum seeker from Zimbabwe, said: “I believe in free movement for everybody.
“I believe in a society where there are no borders at all.
“Everybody except criminals should be free to go to any part of the planet.”
The Government is proposing to change the Bill to make it easier to remove immigrants who have no right to be here and prevent illegal immigrants accessing public services and jobs.