The Conservatives have defended their pledge to cut net migration to “tens of thousands” after Labour said it would never be met.
Treasury Chief Secretary David Gauke told BBC Radio 4’s Any Questions it was an “aim – it doesn’t have a timetable”.
But he said it would “drive policy” in terms of improving the skills of British workers.
It comes after ex-Chancellor George Osborne said the Tories “haven’t a clue” how they will meet the target.
The pledge to reduce net annual migration – the difference in the number of people coming to the UK for a year or more and those leaving – to the tens of thousands was in the 2010 and 2015 Tory manifestos.
Neither Theresa May nor David Cameron has come close to meeting it as prime minister. The most recent figure was 273,000. The last year it was below 100,000 was 1997.
Despite this, the target has been retained in the 2017 manifesto, which states the party will deliver “controlled, sustainable migration” but does not set a timeframe.
The party has not set a deadline for their target of slashing immigration but hopes to do it as quickly as possible, ministers say.
Shadow chancellor John McDonnell said the Tories had “for the third time put before the people unrealistic promises that they know will never be fulfilled”.
He called for “fair, managed migration policy” with numbers to be decided based on what the economy needs and better training for UK workers.
The SNP’s Tommy Sheppard said he did not think the government had any intention of meeting its net migration target.
“It’s a dog whistle to UKIP voters who don’t like immigration to vote Tory,” he told the Any Questions audience.
‘Axe to grind’
Mr Gauke said he was “not belittling migrants” but it was “not sustainable to have net migration of hundreds of thousands for year after year, for decade after decade”.
He said the social pressures would be too much “and that’s why we have to address it”.
George Osborne – who was fired as chancellor last year by Theresa May – has been using his new position as editor of the London Evening Standard to mount an attack on her flagship policy of cutting net migration.
In an editorial, he said Mrs May’s refusal to spell out the impact reducing migration to below 100,000 would have on the economy.
“Either ministers know the damage their immigration policy will do, but won’t tell us; or they have deliberately avoided finding out, because they know the answer will be negative,” he said.
But Conservative candidate Kwasi Kwarteng told BBC News everything about Mr Osborne should be “viewed through the lens of his brutal dismissal” as chancellor by Mrs May.
“He has many axes to grind,” added Mr Kwarteng.
UKIP’s immigration spokesman John Bickley said ministers were trying to “brush off” questions, and that the lack of detail about their plans was staggering.
Liberal Democrat leader Tim Farron told the Press Association: “It is a reminder Theresa May has set immigration targets throughout her time as home secretary and now as prime minister, and has failed to meet them.
“It is about the Conservatives now being basically UKIP.”