Speaking at the end of last week, just weeks before important local elections, McCartney said local communities were enjoying a renaissance under Labour after long years of Conservative neglect.
'[Tory leader] David Cameron may use warm words about our towns and cities, but they stand in stark contrast to the record of his party,' he said.
'Under the Tories, communities up and down the country declined through lack of investment.
'With Labour, our cities are undergoing a renaissance as opportunities increase and residents return. We must not let the Tories put this at risk again.'
The move counters Cameron's long-running campaign to make political capital from the regeneration of Britain's cities.
Within days of winning the Conservative Party's leadership election at the end of last year, he appointed both Michael Heseltine and John Gummer to assess how regeneration could be improved.
McCartney's warning was timed to coincide with the launch of the Tory Spring Conference in Manchester.
A Labour dossier on the Conservative record in cities notes that Manchester's unemployment rate rose to more than 14 per cent under Tories, but is only 4 per cent now.
Richard Leese, Labour leader of Manchester City Council, also joined the attack on the Tories' track record.
He said: 'The people of Manchester have not forgiven the Tories for what they did to our city. That is why they do not have a single councillor here.
'Manchester is thriving and only Labour can secure its future,' he added.