Immigration has been a key reason behind London's high achievement in school standards, the former education secretary Michael Gove has said.
Addressing an international education conference, Mr Gove highlighted the importance of immigrant and refugee families pushing up results.
He said migrant parents had "high expectations" for their children.
But Mr Gove, a leading campaigner for Brexit, said migration had also created "pressure on services".
The capital's schools have consistently outperformed the rest of England in exam results - which Mr Gove linked to the ambitions of migrant families.
Speaking to the Global Education and Skills Forum in Dubai, Mr Gove said: "There's lots of evidence that London having become more diverse has contributed to educational standards rising."
He said that his own experience as a parent in London had shown him that migrant parents often have "extraordinarily high expectations" of the state school system.
Pupils might be "refugees from Somalia or Kosovo", he said, but their families pushed schools to have high standards and often became the most involved parents.
But he said there were costs as well as benefits from migration. And he warned that high levels of migration could undermine "the sense of cohesion".
Mr Gove, debating education policy alongside the former US education secretary Arne Duncan refused to be drawn on whether he agreed with the push for more grammar schools in England. He said that the current education secretary would have to examine whether there was any evidence to justify such an expansion in selection.
