Katie Hopkins has been placed under investigation for alleged hate crime by specialist crime officers after calling asylum seekers "cockroaches" in The Sun.

In a development in the controversy about an opinion piece Hopkins wrote on mass drownings of asylum seekers in the Mediterranean Sea, Scotland Yard has stepped up its investigation.

Hopkins, 40, has faced calls to be sacked following her strongly worded tirade in Britain's biggest-selling tabloid newspaper, which ran beneath the headline 'I'd use gunships to stop migrants'.

The United Nations weighed in against the former Celebrity Big Brother contestant and an online petition demanding her dismissal garnered nearly 300,000 thousand signatures.

The Metropolitan Police said Hopkins' article was being investigated to see if it fell foul of laws against racial hatred and threatening or abusive language, following an official complaint from the Society of Black Lawyers.

"We can confirm that we have received allegations of incitement to racial hatred following an article 17 April," said a spokesman.

"The matter has been passed to assistant commissioner Patricia Gallon at the specialist crime and investigations directorate for consideration. There have been no arrests."

Hopkins has established a lucrative media career upon hard-nosed opinions which reliably prompt enraged reactions from critics on social media, thereby garnering yet more publicity.