Uncontrolled immigration is dangerous and threatens British values, Shadow Home Secretary David Davis has said.
Mr Davis said immigration would be a major election issue
"We must act to secure the future... before it is too late," he told his party conference in Bournemouth.
The Tories would "cut substantially" the numbers coming to Britain by setting separate quotas for economic migrants and refugees, he said.
The annual refugee quota would be about 20,000, but work permits numbers would be dictated by need, he added.
Speaking on BBC 2's Daily Politics, Mr Davis said there were a quarter of a million failed asylum seekers in Britain which would never be removed because of the Human Rights Act, the European Convention on Refugees and other reasons.
He said the Tories would control asylum by asking applicants to make their claims from abroad and by taking away the "inability to remove".
When pushed on the level of immigration quotas, he said: "On the asylum quota it's probably in the order of about 20,000, we will not make that decision yet but that's around where it is likely to be. The other ones are dictated by the facts of the day."
Earlier he told Tory representatives in Bournemouth: "We will tighten control immigration because the country requires it."
He said his party would set a "clear annual limit to the total level of immigration" and ensure it was not breached.
"This will reassure people about their future. And it will sweep away, once and for all, the web of distortion and deceit that poisons this debate.
"I make no apologies for talking about immigration. It is an issue of real public concern. It will be a central issue at the next election.
"If legitimate parties don't discuss it, the real danger is that extremists will," he warned.
He said: "Uncontrolled immigration endangers the values that we in Britain rightly treasure."
But Mr Davis also said Conservatives would never "diminish the contribution that immigrants make".
Liberal Democrat home affairs spokesman Mark Oaten called the plans hypocritical because Michael Howard had said on Tuesday he owed his life to Britain as the son of parents given asylum.
"It is hypocritical for him to now deny modern day refugees the same
Mr Oaten added that Mr Davis had "blown apart" his leader's pledge only to make promises they could deliver.