London: PM Theresa May has said there should be a transition period of "about" two years after Brexit, during which trade should continue on current terms, reports BBC.

EU migrants will still be able to live and work in the UK but they will have to register with the authorities, under her proposals.

And the UK will pay into the EU budget so member states are not left out of pocket.

She hopes this offer, made in a speech in Italy, will unblock Brexit talks. The EU's chief Brexit negotiator Michel Barnier described the speech as "constructive" and said the prime minister had shown "a willingness to move forward".

The prime minister also proposed a "bold new security agreement" and said the UK would be the EU's "strongest partner and friend". On trade, she said the two sides could do "so much better" than adopt existing models.

There was "no need to impose tariffs where there are none now", the prime minister said.

She did not mention how much the UK would be prepared to continue to pay into the EU for two years after it leaves in March 2019, but it has been estimated as being at least 20bn euros (about £18bn). In her speech, Mrs May said the UK would "honour commitments" made while it had been a member to avoid creating "uncertainty for the remaining member states".

She also suggested that the UK and EU would continue working together on projects promoting long-term economic development and the UK would want to "make an ongoing contribution to cover our fair share of the costs involved". When the two-year transition period is up, the UK and EU could move towards a new "deep and special partnership," she said in her speech.

But by March 2019, neither the UK or EU would be ready to "smoothly" implement new arrangements needed: "So during the implementation period access to one another's markets should continue on current terms and Britain also should continue to take part in existing security measures."

Such a period should be "time limited", she said, as neither the EU nor the British people would want the UK to remain in the EU longer than necessary - with its length being determined by how long it takes to set up new systems.

As new immigration systems would take time to introduce, she said "people will continue to be able to come and live and work in the UK, but there will be a registration system - an essential preparation for the new regime".