Dawn Butler and Diane Abbott, Labour MPs for Brent South and Hackney North respectively, said his views on race harked back to the 1950s.
The comments came after the mother of black murdered teenager Stephen Lawrence criticised Mr Johnson's bid.
Mr Johnson is on his party's shortlist to become the Tory candidate for the 2008 mayoral election.
Ms Butler highlighted a 2002 article in which Mr Johnson referred to the Queen being greeted in Commonwealth countries by "flag-waving piccaninnies".
She claimed he also said that he expected, during a mooted visit by Tony Blair to the Congo, that "the tribal warriors will all break out in watermelon smiles to see the big white chief".
The comments came after the mother of black murdered teenager Stephen Lawrence criticised Mr Johnson's bid.
Mr Johnson is on his party's shortlist to become the Tory candidate for the 2008 mayoral election.
Ms Butler highlighted a 2002 article in which Mr Johnson referred to the Queen being greeted in Commonwealth countries by "flag-waving piccaninnies".
She claimed he also said that he expected, during a mooted visit by Tony Blair to the Congo, that "the tribal warriors will all break out in watermelon smiles to see the big white chief".
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