LONDON, June 19 (Xinhua) -- Scottish National Party (SNP) MP Ian Blackford on Wednesday branded Boris Johnson a "racist" in Parliament, sparking a row as the race to succeed Theresa May at the helm of the Tory party is underway.

Blackford said Johnson is unfit to lead the country, highlighting the ex-London mayor's previous comments about Muslims, Africans and Scots.

The MP refused to withdraw his allegation of racism despite being urged to do so by Speaker John Bercow.

Johnson, the former foreign secretary, is widely seen as the favorite to win the contest to become the next Conservative leader and therefore the next prime minister.

He secured a commanding lead in the latest round of voting on Tuesday.