Britain is to take in some of the most vulnerable refugees from the Syrian civil war, including torture survivors and victims of sexual assaults, Deputy Prime Minister Nick Clegg has announced.
No figure is being put on the number of displaced people the UK will take, but hundreds are expected to arrive over the coming year.
The UK is not signing up to take a quota of refugees under the United Nations sanctuary scheme to resettle up to 30,000 vulnerable Syrians in Western nations, but Mr Clegg said the UN High Commission for Refugees backs the Government's plans.
Home Secretary Theresa May will formally confirm the plans in a statement to the House of Commons today, ahead of a debate called by Labour, which wants Britain to join the UNHCR scheme.
Prime Minister David Cameron has resisted signing Britain up to the UN sanctuary programme, arguing that it is not the solution to a crisis which has seen millions of Syrians flee their homes in a three-year civil war.
He stressed that the UK was already the world's second-largest bilateral donor in the crisis, providing £600 million to help victims of the violence in Syria and neighbouring countries.
After coming under pressure from Labour and Liberal Democrats, he told MPs at Prime Minister's Questions last week that he was ready to consider taking in refugees in cases of extreme hardship. Ms May and Foreign Secretary William Hague have been working on details of the scheme over the past week.
Now Mr Clegg has said: "I am pleased to be able to announce today that the UK will be providing refuge to some of the most vulnerable Syrian refugees. The coalition Government wants to play our part in helping to alleviate the immense suffering in Syria.
"The £600 million we have provided makes us the second largest bilateral donor of humanitarian aid in the world. But as the conflict continues to force millions of Syrians from their homes, we need to make sure we are doing everything we can.
"We are one of the most open-hearted countries in the world and I believe we have a moral responsibility to help."
Explaining the criteria under which refugees will be selected for admission to the UK, Mr Clegg said: "The UN High Commission for Refugees - which backs our new resettlement programme - has said the highest priority should go to women and girls who have experienced or are at risk of sexual violence, the elderly, survivors of torture, and individuals with disabilities, so that's who we'll target.
"Sadly we cannot provide safety for everyone who needs it, but we can reach out to some of those who need it most.
"On top of that, we'll continue to support the peace talks currently taking place in Geneva, because only a political resolution between the (Bashar) Assad regime and Syrian opposition will provide a permanent end to the suffering.
"Britain has a long and proud tradition of providing refuge at times of crisis. This coalition Government will ensure it lives on."
No target will be set for the numbers of refugees to be admitted, with the UK instead working with the UNHCR on a case-by-case basis to identify those most in need of assistance.
Refuge will be offered to some of those most traumatised by the crisis, including vulnerable women and children, who are expected to arrive on a gradual basis over the coming months.
Shadow home secretary Yvette Cooper said: "Vulnerable Syrian refugees, torture victims, abandoned children and those struggling to cope or survive in the camps desperately need sanctuary and Britain has a moral obligation to help.
"I am very glad the Government has finally bowed to pressure before tomorrow's opposition vote.
The UK representative of the UN High Commissioner for Refugees, Roland Schilling, said: " This decision will help to provide much needed solutions for vulnerable Syrian refugees many of whom have been deeply traumatised and face immense hardship.
"It is also a concrete and important gesture of solidarity and burden sharing with the countries neighbouring Syria as they continue to bear the brunt of the refugee crisis.
"Today's decision is an encouraging and important step, reaffirming the UK's commitment and contribution to international relief efforts in support of more than 2.3 million Syrian refugees and the countries hosting them. ."
Refugee Council chief executive Maurice Wren said: "This news, quite simply, will transform people's lives.
"What's more, it also sends an important message to the rest of the world: Britain has a proud tradition of protecting and welcoming refugees and we will continue to lead the way in offering refuge to people in their greatest hour of need.
"We commend the Government for upholding this reputation by going the extra mile and offering protection to some of the most vulnerable refugees who will now have chance to rebuild their lives in safety. "
Amnesty International UK director Kate Allen said: "This move is long overdue but of course it's never too late to do the right thing.
"The government's line on this has been shameful, with months of refusal and weak arguments.
"It was a never a matter of choosing between helping refugees in the region or helping refugees in this country - and it's an enormous relief that the government has finally changed its mind on this.
"For some of the most vulnerable refugees, this offer is a lifeline. It's literally a matter of life and death ."
Speaking to BBC Breakfast, Ms Cooper said: "This is about the most vulnerable refugees of all in the dreadful Syrian conflict - we are talking about the torture victims, abandoned children.
"What we know is that it is important for all countries to contribute to do their bit to provide sanctuary, so if Britain can do that as part of the UN programme then that can add up to very many people helped right across the world.
"So I think it is a good thing that the Government has completely reversed its position - just seven days ago they were refusing to do anything at all to help with providing sanctuary in this way.
"But it is slightly surprising that they are still refusing to sign up to the UN programme and to do this alongside other countries."
Justin Forsyth, chief executive of the charity Save the Children, said: "We welcome this move to help Syrian refugees in the UK.
"It is the right moral thing to do and will help vulnerable children, many injured and traumatised.
"But the number one priority must remain the appalling humanitarian crises in Syria where millions of children are starving, cold and frightened, many cut off without aid."