The Mayor of London, Sadiq Khan, has addressed the recent arrest and subsequent de-arrest of a street preacher outside Southgate tube station.

Video footage of Oluwole Ilesanmi being arrested by police for a "breach of the peace" went viral on social media and has now been viewed over 2 million times.

Police arrested Mr Ilesanmi after a member of the public complained that he had made 'Islamophobic' comments.  No further action was taken and Mr Ilesanmi was subsequently de-arrested.

However, a complaint was later lodged against Enfield police over their handling of the situation after Mr Ilesanmi said he had been released by police some distance from Southgate and was only able to make his way back with the help of a member of the public who paid for his bus fare.

The incident has given rise to concerns about freedom of speech for Christians.

Addressing Mr Ilesanmi's arrest during Mayor's Question Time at the London Assembly on Thursday, Mr Khan said: "I expect the police to take this matter seriously."

Although Mr Khan said it would be inappropriate for him to comment on the specific case in light of the ongoing review by the borough's Professional Standards Unit, he defended the right of police to investigate allegations of criminal offence.

"It's always been clear that freedom of speech is critical and must be protected but also the police must be able to investigate when allegations are made of a criminal offence," he said.

"Police officers have to strike a difficult balance on this issue on a regular basis and in complex circumstances, such as policing protests and public order incidents."

He said the London Metropolitan Police appreciated the "sensitivities" involved and took "seriously" the duty to be balanced.

He added: "The Commissioner and I both believe that the law should be applied to all Londoners irrespective of their background and beliefs and without fear or favour. As part of this, our police officers are rightly expected to always uphold the highest standards."

Responding to his comments, assembly member and Christian, David Kurten, said free speech was an "important" right and that there were aspects of Mr Ilesanmi's arrest that he had found "disturbing", including the police taking away his Bible.

He said there was a fear, particularly among Christians, that freedom of speech was being "undermined".

Pressing the mayor on whether Christians could openly read from any part of the Bible without fear of arrest, Mr Khan refused to rule out the possibility of similar incidents happening again in the future.

"There's not an unlimited right to freedom of expression or free speech. There are limitations and there's a balance that needs to be done," said Mr Khan.

"But I'm quite clear in my own views - we should go as far as we can to uphold that really important principle [of free speech] and that includes discourse about religion."