"Heads must come out of the sand" about the scale of immigration to Britain, according to one senior Conservative MP.
MP for Mid Sussex, Nicholas Soames, opened a backbench business debate on immigration, on 6 September 2012.
Mr Soames warned MPs the "stakes are indeed very high" with difficult decisions to take against "unforgiving" timescales.
The issue of immigration was, he said, of "fundamental importance to the future of the country".
He added that a Commons debate had been chosen by the Backbench Business Committee in response to a petition launched by MigrationWatch on the government's website last autumn, which received more than 100,000 signatures within a week.
Former Labour minister Frank Field spoke about Britain hosting the London 2012 Olympic Games, saying he was "delighted" by the athletes who had come to make a new life and "were so committed to us that they actually wanted not only to participate but to win for this country".
He said he had feared the Games might present the opportunity for a terrorist outrage, but was pleased he had been wrong.
He told MPs: "We have so many people who come here and are so committed and yet at the same there are some, so far as we know, second generation, who harbour such terrible thoughts in their hearts about us that they actually want to take terrible action against us."
The motion called on the government to reduce immigration to a level that would keep the UK's population significantly below 70 million.
Figures released last week showed that net migration to the UK has fallen but remains at more than double the government's target of fewer than 100,000 a year.
The UK population currently stands at about 62.6 million - the Office for National Statistics projects this will reach 72 million in 2032 and 81 million by 2060.
The SNP's Pete Wishart dismissed the motion as "nasty, silly, and ridiculous" and said it was something that "could almost be from a shady authoritarian regime".
Mr Wishart also questioned what "all necessary steps" to reduce immigration could really mean.
Shadow immigration minister Chris Bryant said Britons worried about foreigners settling in the UK were not "bigots".
Mr Bryant told MPs: "It's absolutely vital that we have a robust, firm, workable, controlled immigration system that is fair to the resident British nationals and to migrants who seek to come here."
Responding to the debate for the first time in his new role as immigration minister, Mark Harper said the government remained committed to its manifesto target of bringing net immigration down to the tens of thousands.
He said: "Reducing net migration and tackling abuse are completely compatible with continuing to attract the brightest and the best.
"Immigration can be beneficial to Britain but the unsustainable levels we have seen have been damaging. That was why we said would get a grip."