Net migration is the difference between the numbers of people moving to the UK for more than a year, and the numbers of people leaving the UK to live elsewhere for a year or more.
UKIP, which is seeking to bounce back from a poor set of local election results, said the Conservatives could not be trusted over the issue and only it had the “political will” to bring about a sizeable reduction in immigration, before and after the UK leaves the European Union.
Announcing its policy for June’s general election, immigration spokesman John Bickley said England was the “sixth most overcrowded country in the world”, with immigration levels putting pressure on public services and community cohesion and depressing wage levels for British workers.
Under its “one-in, one-out” plan, annual levels of migration would be reduced from 600,000 to about 300,000. There would be a five-year moratorium on unskilled and low-skilled labour, although seasonal workers, such as fruit pickers, would still be able to apply for six-month visas. (Under current rules anyone moving to the UK less than a year is not counted for the purposes of migration figures.)
EU workers will still apply until Brexit, expected to happen in 2019, and the common travel area with the Republic of Ireland is expected to be maintained, UKIP believes it can bring net migration into balance within five years.
Although it will not set annual targets, it is committed to then keeping the average figure at zero over a rolling five year period.
“Net migration has been the equivalent of a city the size of Birmingham over the past three years,” Mr Nuttall said. “This is clearly unsustainable and it is clearly unfair, particularly to inner city communities.”
Of the 596,000 people who came to the UK in the last year, 268,000 were from the EU while 257,000 were from elsewhere in the world, with the remaining 71,000 being British citizens returning. At the same time, 323,000 people left the UK.
Mr Bickley said UKIP still wanted to attract the “brightest and best” to the UK, including foreign students, but there could not be an unlimited number of people coming to study due to the pressures it placed on housing and other infrastructure.
He said the number of visas for seasonal workers from abroad would be gradually reduced as British workers were trained to take their places.