Sadiq Khan today mocked Zack Polanski by answering his question in the London Assembly in Urdu.

The London mayor used the South Asian language to respond to the Green Party leader after Mr Polanski recently spoke it in a by-election campaign video.

Mr Polanski is a member of the London Assembly but is hoping to soon be elected to the House of Commons as MP for Holborn and St Pancras.

He is standing in next month's by-election in the north London constituency, which was triggered by the resignation of ex-prime minister Keir Starmer as the local MP.

'I thought as the member is so proficient in Urdu that I would speak in Urdu,' Lord Khan said, after he used the language to reply to Mr Polanski at Mayor's Question Time on Thursday.

The Labour politician added: 'I was worried the question may be in Urdu. And for those Urdu speakers, I apologise if I spoke with a Russian accent.'

The exchange came after Mr Polanski this week released a by-election campaign video in which he addressed Holborn and St Pancras voters in Urdu.

Urdu is the national language of Pakistan and is spoken across South Asia.

Responding to a clip of Lord Khan to Mr Polanski in Urdu, Tory ex-Cabinet minister James Cleverly - who is now running for London mayor - posted on X: 'Fair play. This is funny.' 

In his by-election video, Mr Polanski used Urdu to encourage local residents to vote for him as the Green candidate at the Westminster contest on October 8.

He later released a campaign video in French in an apparent attempt to troll critics – including Tory shadow ministers – of his previous video in Urdu.

The Green leader appealed for people in the north London seat to 'votez pour les verts' next month.

By switching to French, Mr Polanski used a language spoken by far more people in Holborn and St Pancras than speak Urdu.

Figures from the 2021 census show there were 2,488 with French as their main language in the constituency, compared to just 156 who spoke Urdu.

Urdu is spoken primarily in Pakistan and India, but just 3 per cent of the population of Holborn and St Pancras are Indian and less than 1 per cent are Pakistani.

About 10 per cent of voters in Holborn and St Pancras are Bangladeshi, but the official language of Bangladesh is Bengali.

In response to Mr Polanski's by-election video in Urdu, Tory local government spokesman Katie Lam tweeted: 'Here's the leader of the Green Party, campaigning in Urdu. 

'Attempting to appeal to group-based grievances by campaigning in foreign languages is poisonous.

'We must ban this practice for good. Politics in our country should be conducted in the language of public life.'

Fellow Tory MP Helen Whately, the shadow work and pensions secretary, told Times Radio: 'I'm concerned to see this campaigning in other languages.

'Politicians should be campaigning in the languages of the United Kingdom. So for instance in London, I'd be expecting the candidates to be campaigning in English, not in other languages.'

A Green Party spokesman told the Daily Mail: 'The Greens believe that democracy doesn't discriminate by languages spoken. Many people are bilingual.

'Holborn and St Pancras is a true reflection of the diversity of London and of our country and we choose to embrace and celebrate that.

'If we want to speak to people who speak Urdu, it makes sense to speak to them in Urdu. We're proud to reach voters in as many languages as possible.'

Sir Keir resigned as MP for Holborn and St Pancras at the beginning of this month, despite him having previously said he would stay in the Commons until the next UK general election, which is not due until 2029.

Mr Polanski is hoping to build on the Greens' momentum from the May local elections, which saw the party placed second behind Labour in council wards within the constituency.

He is likely to be the most serious electoral threat to Labour's dominance in the seat, which the party has held since it was created in 1983.