Boris Johnson embroiled in race row after 'part-Kenyan' jibe against Barack Obama

Boris Johnson has found himself at the centre of a racism row after he suggested Barack Obama harbours anti-British sentiments because of his Kenyan ancestry. The outgoing Mayor of London drew criticism after a penning an anti-EU piece for The Sun newspaper to coincide with the US President's visit to the UK.

Writing about Obama's decision to remove a bust of Britain's war time Prime Minister Sir Winston Churchill from the Oval Office, Johnson said: "Some said it was a snub to Britain. Some said it was a symbol of the part-Kenyan president's ancestral dislike of the British Empire – of which Churchill had been such a fervent defender."

The attack came as Obama threw his support behind the 'remain' campaign ahead of the EU referendum on 23 June. Johnson, a biographer of Churchill, had backed Obama when he first successfully ran for the White House in 2008. But now the American-born Conservative faces accusations of racism.

"The nasty party is back," Labour's Chuka Umunna declared. "Zac Goldsmith has played on Sadiq Khan's Muslim heritage to try to link him with radical extremists, and today Boris Johnson has played on Barack Obama's Kenyan ancestry to question his motives around the EU referendum debate." The pro-EU campaigner added: "This is beyond the pale and base politics of the worst kind. We may have come to expect this from Donald Trump – but Goldsmith and Boris should know better, and Londoners deserve better."

Shadow chancellor John McDonnell took to social media site Twitter to rail against Johnson, urging the Uxbridge and South Ruislip MP to withdraw his remarks and claiming it is "yet another example of dog whistle racism from senior Tories".

The row comes on the second day of Obama's visit to the UK, where he will meet The Queen to celebrate the monarch's 90th birthday and hold talks with pro-EU Prime Minister David Cameron.

"The EU doesn't moderate British influence – it magnifies it. A strong Europe is not a threat to Britain's global leadership; it enhances Britain's global leadership," Obama wrote in The Daily Telegraph.

"The US sees how your powerful voice in Europe ensures that Europe takes a strong stance in the world, and keeps the EU open, outward looking, and closely linked to its allies on the other side of the Atlantic. So the US and the world need your outsized influence to continue – including within Europe."