Mr Farage was speaking on LBC in the wake of the Nice terror attack last week, which has raised questions about the capability of the French security and intelligence community.
He said: “I have to say I am worried about France and I have been worried working in Brussels for some time.
“Just large parts of that city are now virtually lawless.
“Very difficult in the centre of Brussels for women at night to walk alone, particularly if they are blonde-haired.
“They get repeatedly stopped and pestered and something has gone badly wrong.”
Molenbeek, a Brussels suburb which has been linked to several terrorists and terror plots, has been identified as an area of concern for Belgian authorities and labelled Europe’s “jihadi capital”.
During his two-hour radio show, Mr Farage discussed whether the recent attacks in Nice would increase the likelihood of Donald Trump and Marine Le Pen being elected.
Mr Trump has previously called for a ban on Muslims entered the United States while Ms Le Pen has said the Nice attack is proof of Islamic fundamentalism’s rise.
One caller to LBC backed the use of military force to combat ISIS in Syria and Iraq, saying: “I think we should get in there… and Trump seems to be the person who is actually saying something about it.”
Last year Mr Trump sparked outrage by claiming there are parts of London and other European cities which have become “no-go” areas for police.
He said: “We have places in London and other places that are so radicalised that the police are afraid for their own lives.”
Over the weekend Ms Le Pen, leader of the French National Party, called on the French Interior Minister to quit.
Bernard Cazeneuve has been in charge while both the Nice and Paris terror attacks have taken place.
Ms Le Pen said: “In any other country in the world, a minister with a toll as horrendous as Bernard Cazeneuve – 250 dead in 18 months – would have quit.”