Immigrant workers trap British-born people in unemployment, according to research to be published this week by Frank Field, the former welfare reform minister.

The research, based on an analysis carried out by the House of Commons library, shows that the higher the level of immigration in an area, the harder it is for the unemployed to come off jobseeker’s allowance.

Although the problem exists everywhere with high immigration, it is acute in southwest England, the analysis shows, in places such as Bristol, Cheltenham, Plymouth and Weymouth.

“The government has got a choice here between simply feeding the labour market with migrant workers and doing something about welfare reform,” said Field.

“The government has set itself a target of getting 80% of working-age people into employment. At the rate it is going, that will take 30 years.”

The study found that across the country 20% of the variation between areas in the numbers leaving benefit was due to immigration. In the southwest this rose to 30%.

The findings follow a Statistics Commission report, requested by Field, which confirmed findings in The Sunday Times that more than 80% of new jobs since 1997 had gone to people born outside the UK.

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