Diane Abbott's decision to educate her son privately shows that London's state schools face "a very big challenge", education minister Stephen Twigg said this week.
Miss Abbott caused a furore when it emerged that she was sending her 12-year-old son James to the pound;10,000-a-year City of London school.
The outspoken left-wing MP for Hackney North and Stoke Newington was branded a hypocrite because of her earlier attacks on private and selective schools.
She criticised Prime Minister Tony Blair after he rejected Islington schools and sent his two oldest sons to the London Oratory school which selects by interview.
Mr Twigg told The TES that he was committed to making London "a world-class learning and creative city".
Earlier he had told educationists and businessmen at a reception organised by Business First that he wanted to see London schools scoring above the national average.
Mr Twigg told The TES: "What happened with her (Miss Abbott's) decision, demonstrated that we still have a very big challenge in London, especially in boroughs where no tradition of faith exists." Mr Twigg said he remained confident that standards would rise in London and said specialist schools remained at the "heart of current plans for improvement".
However, another of Miss Abbott's parliamentary colleagues was less sanguine about her decision and the implications for the reputation of London's state schools.
Brian Sedgemore, MP for Hackney South and Shoreditch, said Miss Abbott was effectively telling parents they had no hope of getting a good state education for their children anywhere in London.
Miss Abbott declined to comment, but in a letter to the Mail on Sunday she said she pleaded "guilty to believing in one thing and doing another".
She wrote that she has risked her career to put her son's education first and had "explored every possibility" to "make the state school option work".
She added: "I was so desperate, I seriously considered sending my son to Jamaica for his secondary education."
The TES last week revealed that the schools Miss Abbott shunned appeared to be outstripping the rest of England.
Professor Tim Brighouse, London schools commissioner, revealed new figures which divide schools' provisional GCSE results for this year into 10 bands according to the percentage of pupils eligible for free meals. In every band the proportion of pupils getting five Cs or better at GCSE was higher in London.
David Levin, head of the City of London School, said Miss Abbott's decision to send her son to the school was "because it was the right choice for James. It's not sending out a message that London's state schools are rubbish it's just the right choice for her son".
He added that she was impressed that his school works with five inner-city schools to raise standards and that it is owned by a local education authority.