Government plans to cut net migration to the "tens of thousands" in four years are likely to fail, a report has found.
Prime Minister David Cameron and Home Secretary Theresa May say they want to bring annual net migration down from the current 242,000 to just "tens of thousands" of people by 2015.
But they will only achieve half the desired effect, at best, according to analysis by Oxford University's Migration Observatory. Reforms to the immigration system will not help reduce numbers far enough or fast enough, leaving net migration at around 165,000 by 2015.
Shadow home secretary Yvette Cooper said the report showed that the Government has "no workable policies" to meet its promise and that its immigration policy was in "complete disarray".
Changes to work and student visas are expected to cut net migration by a respective 11,000 and 56,000 people by 2015, Government figures show.
The Migration Observatory also found that changes to family visas will cut the numbers by 8,000 at most, while plans to make it harder for migrants to settle in the UK are unlikely to reduce migration flows until 2016.
Dr Scott Blinder, senior researcher at the observatory, said: "The Government's current policies only look likely to reduce net migration by about 75,000 at best, which would mean that further reductions of more than 67,000 would be needed to meet the tens-of-thousands net migration target."
To achieve the 100,000 target, the Government will either have to further tighten immigration rules or "reconsider the target or the timeframe in which they intend to deliver it", the report said.
The Government could also hope that more British and EU nationals emigrate from the UK or that current assessments are "way off the mark". But the report said these two options are "pretty unlikely".
Responding to the report, Immigration Minister Damian Green repeated the Government's pledge to cut migration to less than 100,000 by 2015. He said: "For too long the immigration system was allowed to get out of control. This Government will tackle abuse of the system and get net migration reduced back down to the tens of thousands in the lifetime of this parliament."