"Heads must come out of the sand" about the scale of immigration to Britain, a Conservative MP has said.
Nicholas Soames, MP for Mid Sussex, warned MPs the "stakes are indeed very high" with very 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.
He said: "This is a clear indicator of the very great public concern about the scale of immigration to this country."
The motion, he added, calls on the Government to take all necessary steps to get immigration down to a level that will stabilise the UK's population as close as possible to its present level, and certainly, significantly below 70 million.
He noted that immigration was a "natural and essential part of an open economy", but he added: "We are at the present time experiencing the greatest wave of immigration to our country in nearly 1,000 years."
Mr Soames, grandson of former Prime Minister Sir Winston Churchill, turned his fire on Labour, who he said had bequeathed the country a "chaotic, ill-thought-out and deeply irresponsible policy" on immigration, which had "changed the face of this country".
He said the 2011 census results showed that in the last ten years, the population increase had been the largest for any period since the records began since 1801. And if the net migration average of 200,000 a year continued, the country's population would hit 70 million in 15 years' time - a 7.7 million increase, with five million new immigrants and their children.
He said: "The Prime Minister has given his word that this Government will bring net migration down to tens of thousands. Failure to do so will leave our population rising inexorably, pressure on our already hard pressed public services building up relentlessly and as a result, social tension mounting. We must stop this happening."