The wealth gap between whites and minorities in the United States has reached an unprecedented level, according to a report released by the Pew Hispanic Center on Tuesday.

"The median wealth of white households is 18 times that of Hispanic households and 20 times that of black households," the Pew Research Center's Social & Demographic Trends project found.

Between 2005 and 2009 the median wealth of Hispanic households in the United States shrank 66 percent, and that decline "was the largest among all racial and ethnic groups," according to the study.

In the same period the wealth of African American households dropped 53 percent while white households lost 16 percent.

Expressed in dollars the contrast is stark, and blacks remain the poorest group of the three. Hispanics are the largest minority in the country with 16 percent of the population, followed by African Americans with 12 percent.

In 2005, according to the study, the median net worth of white households was $134,992 compared with $18,359 for Hispanic households and $12,124 for black households.

In 2009 the median net worth of white households was $113,149 compared with $6,325 for Hispanics and $5,677 for blacks.

The disparity, say study authors Rakesh Kochar, Richard Fry and Paul Tylor, are the biggest since the government began publishing data and "roughly twice the size of the ratios that had prevailed between these three groups for the two decades prior to the Great Recession."

The bursting of the housing bubble in 2006 and the recession that followed from the end of 2007 to mid-2009 "took a far greater toll on the wealth of minorities than whites," according to Pew.

The crumbling of housing prices was the main cause of the recent erosion of household wealth for all groups, but Hispanics were hit the hardest.

Pew attributes that result to the fact that Hispanics have a greater probability of living in areas where the construction industry's decline was concentrated.

Net worth also tanked because of a 42 percent increase in the median levels of credit-card debt and student loans, Pew says.

In 2009, according to the report, nearly 25 percent of both Hispanic and black households had no other asset but a vehicle, compared with a scant 6 percent of white households in the same straits.

But not only has inequality in wealth increased between whites, blacks and Hispanics, the study says, but so have the differences within each of these groups.

"The top 10 percent of Hispanic households saw their share of all Hispanic household wealth rise from 56 percent in 2005 to 72 percent in 2009," according to the report.