The study by cross-party group Operation Black Vote (OBV), which campaigns for a fairer vote across various communities in Britain, found the number of seats where ethnic minority voters could decide the outcome had rocketed by 70 per cent compared to the 2010 election.
"The black vote has never been so powerful. This is great news for all those who thought we could never effect change," OBV spokesperson Simon Woolley said.
"With this political leverage I'm sure many will want to demand greater race equality. This research is a political game-changer - above all, if ethnic minority communities and politicians respond positively to it, democracy wins," he added.
In 2001, the census showed Britain's ethnic minority population was 7 per cent, and this had grown to 11 per cent by the 2011 census.
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According to the OBV study, the ethnic minority vote will be crucial in swing seats from the Midlands to the south coast, across to East Anglia, and in the north-east.
Besides growing in numbers, minorities are moving out of inner cities into more marginal seats.
This will increase their electoral importance in 2015 and is expected to feature prominently in future elections.
The party secured only 16 per cent of the minority vote at the last election, compared with 68 per cent for Labour.
Experts say the trend will continue and may change the dynamics of British politics in the coming years.
The Conservatives' race deficit will cost them between 20 and 40 seats in 2015, according to related calculations by Prof.Anthony Heath of Oxford University, who has been studying ethnic demographic changes and their effects on elections.
"Minority voters can be won away from Labour, but only if you make active efforts, including addressing their concerns. There is little sign of long-term erosion from Labour," he said in reference to the estimates for a forthcoming book.
"Registered BME voters are as likely to vote as other groups. And they have specific concerns that the inequalities of Britain in general are more clearly experienced by those in their communities.