A "retreat" of white Britons from areas where minorities live is limiting cultural integration, research by think-tank Demos says.

Analysis of Census 2011 figures show 45% of ethnic minorities in England and Wales live in areas where less than half the population is white British, while 41% live in wards that are less than half white.

Trevor Phillips, former chairman of the Equalities Commission and Demos Associate, said white Britons choosing not to live in minority-dominated areas "ought to make us a little anxious".

He said: "This research shows a welcome minority advance into areas previously only the preserve of the white majority. What ought to make us a little anxious is the 'majority retreat' – white people leaving minority-led areas and not being replaced – which isn't good for integration."

The 4.1 million ethnic minorities who now live in white minority areas is a significant increase from the 2001 Census, when only around one million minority Britons lived in such wards.

Demos said: "Researchers attribute this mainly to white British people choosing not to move to minority-dominated areas

"Departing white British are replaced by immigration or by the natural growth of the minority population. The end result of this process is a spiral of white British demographic decline."

However, integration between ethnic minorities is more common than in 2001. Demos said minority white areas were generally multi-minority, since new minorities such as Somalis have taken up housing vacated by established minorities.