Justice Minister Michael Gove on Tuesday warned that Britain faces higher immigration if it remains in the European Union, backing a Vote Leave campaign for the country to adopt a "more effective and humane," points-based immigration system.
"At the moment any EU citizen can come to the UK to settle, work, claim benefits and use the NHS (National Health Service)," said Gove, who is one of the leading ministers publicly opposing Prime Minister David Cameron's campaign for Britain to remain in the EU after a referendum on June 23.
"We have no proper control over whether that individual's presence here is economically beneficial, conducive to the public good or in our national interest," Gove said.
"As long as we are in the EU we cannot control our borders and cannot develop an immigration policy which is both truly humane and in our long-term economic interests," he said.
In a remark that appeared to be partly aimed at voters with family members in non-EU nations, Gove said that "as the price of EU membership, we have to impose stricter limitations on individuals from other nations whom we might actively want to welcome."
"Whether it's family members from Commonwealth countries, the top doctors and scientists who would enhance the operation of the NHS, or the technicians and innovators who could power growth, we have to put them at the back of the queue behind anyone who's granted citizenship by any other EU country," he said.
Some campaigners who have non-EU family members have backed a British exit from the EU, or Brexit, because they feel disadvantaged by tougher immigration rules introduced by the government amid claims that migration from EU nations was too high.
Syed Kamall, a Conservative who represents London at the European Parliament, last month said immigration was "a crucial deciding factor" in his backing of Brexit.
Kamall said he "wants to see an immigration policy that is balanced and fair - where we treat everyone outside the UK equally whether they are from an EU country or not."
"As the son of immigrants who came from a non-EU country, this is my deeply held conviction on an issue that matters deeply to me," he said in a statement on his decision to back Brexit.
Immigration is expected to be a key issue in campaigning ahead of the referendum. The two main campaign groups have accused each other of using scare tactics over immigration, finance, business, security and other issues.
On Monday, Chancellor of the Exchequer George Osborne presented a Treasury report claiming that the average British household would lose 4,300 pounds (6,100 dollars) annually if Britain leaves the EU.
The Commonwealth includes 53 states, most of which were once ruled directly or indirectly by Britain.
As Britain rebuilt its post-war economy in the 1950s and 1960s, it encouraged immigration from Commonwealth nations, especially those in the Caribbean and the Indian sub-continent.