Opposition to immigration drops when people are told about the economic benefits of net migration, new research indicates. A YouGov poll found that the proportion of those questioned who viewed immigration negatively dropped from 63% to 54% after they were told that the government's financial watchdog believes that higher immigration will help the economy grow and ease pressure to cut spending.

The results have prompted fresh demands for the debate on immigration to centre on facts as opposed to fear-mongering and inflammatory rhetoric.

The Office for Budget Responsibility says that, if net migration were stopped, in five years the public sector's net debt would be £18bn higher than if it continued. Within 50 years, the debt would soar from 74% of GDP to 187% – higher than Greece's 161% debt.

Increasing immigration would prove controversial, because the coalition has pledged to reduce the annual figure to "tens of thousands" by the end of this parliament, from the current official level of about 260,000 a year.

YouGov found that, after being told the "full facts", the proportion of respondents holding positive views about net migration grew from 32% to 39%. The numbers wanting an end to all immigration dropped from 16% to 12%, and those advocating a small number of skilled migrants fell from 47% to 42%.

Barbara Roche, the former MP and Labour immigration minister, who chairs the campaign group Migration Matters, said: "Those opposed to immigration ignore what for them is an inconvenient truth. It's not that we cannot afford more immigration, rather that we cannot afford not to have immigration."

Roche, whose organisation says it wants "an open and honest debate about the issues of migration", added: "These polling figures show that when the full facts of migration are presented to the British people, they begin to recognise that simple truth. The challenge politicians of all parties face is presenting the facts about immigration in a way the public can trust and understand".

The Home Office has rejected the OBR's claims that higher immigration could cut billions from Britain's deficit. The former immigration minister Damian Green said the OBR report failed "to take account of the costs of immigration".

Organisations such as Migration Watch have called for an end to net migration, but critics accuse it of ignoring the issue's economic dimension.

The Tories were recently accused by former prime minister Gordon Brown of adopting Enoch Powell-style rhetoric on immigration in their efforts to fight off advances by Ukip. Last week, Tory MP Chris Skidmore blamed the escalating A&E crisis on immigrants.