London: The leaders of a far-right British party, one of whom gained widespread attention after a message she posted online was retweeted by US President Donald Trump, have been found guilty of religiously aggravated harassment.

Paul Golding, 36, leader of the anti-immigration Britain First party, and his deputy Jayda Fransen, 31, were convicted of filming and harassing people they believed were involved in a rape trial involving a number of Muslim men at a court in Kent.

They posted their actions on the Britain First website and delivered offensive leaflets to homes in the area where those involved in the case lived, prosecutors told Folkestone magistrates court.

"The prosecution case demonstrated these defendants were not merely exercising their right to free speech but were instead aiming religiously aggravated abuse at innocent members of the public," Chief Crown Prosecutor Jaswant Narwal said in a statement.

Golding was jailed for 18 weeks and Fransen 36.