WASHINGTON, United States – A new report has found that the number of Caribbean and other illegal immigrants living in the United States has declined for the first time in two decades.

The report, issued yesterday by the Pew Hispanic Center, a Washington-based independent research group, is based on an analysis of 2009 census data.

It attributes much of the decline to a sharp drop-off in illegal immigrants from the Caribbean, Central America and South America.

It said that illegal immigrants decreased by eight per cent as jobs declined in America because of the economic recession.

The center said that in March 2009 – the most recent figures – there were 11.1 million unauthorised immigrants in the US, compared to 12 million in March 2007.

"The decrease represents the first significant reversal in the growth of this population over the past two decades," the report states.

The report said that illegal immigrants from the Caribbean, Central and South America, decreased by 22 per cent in the 2007-2009 period.

The US Immigration and Customs Enforcement (ICE) agency said that, in recent years, it has deported an increasing number of illegal immigrants, reaching a high last year of more than 389,000 people.

It, however, points out that despite the decline, the population of unauthorised immigrants was nearly a third larger in 2009 compared to 2000, and it is three times larger than in 1990.

Among the report's other findings was that nearly half of unauthorised immigrants living in the country in 2009 arrived in 2000 or later.

The center said that illegal immigrants comprise about 28 per cent of the foreign-born population in the US, down from 31 percent in 2007.

It said the unemployment rate for illegal immigrants in March 2009 was 10.4 per cent higher than that of US-born workers or legal immigrants, who had unemployment of 9.2 per cent and 9.1 per cent, respectively.

New York Mayor Michael Bloomberg, an outspoken advocate of welcoming more immigrants to the US, said he was not surprised by the study's findings.

"It exemplifies what I've been saying all along," he told reporters. "Not totally, but generally, people come here from around the world - whether they come here legally or illegally - to work, to build a better life for themselves and for their families. And when our economy is down, it's just tougher to get a job."