The mayor of Rotterdam – the only immigrant Muslim mayor of a major European city – has challenged right-wing politician Geert Wilders to spell out how he plans to reduce the Moroccan-born population of the Netherlands.

Mr Wilders faces prosecution for allegedly inciting hatred when he led supporters in anti-Moroccan chanting at a rally last year. When the crowd shouted that they wanted fewer Moroccans in the country, Mr Wilders infamously replied, “We can take care of that.”

Ahmed Aboutaleb – born in Morocco where his father was a Sunni imam before the family moved to the Netherlands in 1976 – spoke of his “hurt” when his now-elderly parents asked him when they would have to leave their adopted country.

“My father worked at two jobs so that I could afford to go to university and get on in the Netherlands,” said Mr Aboutaleb, who was invited to the White House last February for a four-day international conference on countering extremism.

“Now my parents are scared and I too feel their pain. My father says he hears there have to be fewer people like him, not because he has done anything wrong but solely because he is a member of a particular ethnic group.

“So I want to know from Wilders – when are you going to start sending them back? Wilders has said he is going to organise it, so society has a right to know exactly how he plans to do it and when. That way we can let him know what we think of his plans.”

The latter was a thinly veiled reference to the fact that the chanting episode appears to have been the main element in putting paid to Mr Wilders’s hopes of an anti-austerity landslide in the European elections last year.

Instead of leading to a surge of popular support in line with Marine le Pen’s historic victory in France, the Freedom Party’s share of the vote fell from 17 per cent in 2009 to 12.2 per cent and a lacklustre fourth place.

Mr Wilders hit back, tweeting that he had outlined his plans in detail last year, saying they would involve a combination of limiting immigration from Islamic countries, introducing measures to stimulate voluntary repatriation, and deporting criminals.

This is not by any means the first bad-tempered exchange between Mr Wilders and Mr Aboutaleb.

In 2006, when Mr Aboutaleb was appointed secretary of state for social affairs, Mr Wilders claimed his dual citizenship suggested “dual allegiance”.

When Mr Aboutaleb was named Mayor of Rotterdam in 2008, Mr Wilders commented that if he wanted to become mayor, “he should become Mayor of Rabat”, adding that his appointment was “as ridiculous as appointing a Dutchman Mayor of Mecca”.