A majority also dispute the Government's assertion that those coming into the country have helped the economy.

The research, carried out by YouGov for pressure group Migrationwatch, emerged as politicians battle to dominate the immigration agenda.

David Cameron was boosted when another poll suggested he was more trusted to deal with the controversial issue than Gordon Brown.

The Tory leader has condemned ministers for "incompetence" and called for an overall limit on immigration levels.

He has also attacked the Prime Minister for echoing the BNP with his "British jobs for British workers" slogan.

The latest study found 85% of people thought that immigration was putting too much pressure on public services, with only 10% disagreeing.

Some 81% supported the view that the level of immigration should be reduced substantially, while 14% rejected it.

When asked if they believed immigration had been generally positive for the UK economy, 35% said it had compared to 54% who thought it had not.

Migrationwatch chairman Sir Andrew Green said: "These figures show that now the scale of immigration and its consequences are now being better understood and people are deeply concerned at what is going on."