Theresa May is to unveil her vision for Britain's future outside of the EU during a speech on the status of Brexit negotiations in Florence next week.
The speech to be held in the Italian city on the 22 September is likely to be seen as a bid to break the deadlock in withdrawal negotiations, which resume in Brussels three days later.
It comes amid warnings that progress in talks on the UK's divorce deal has been too slow for discussions to move on to the question of a future trading relationship as Britain desires.
On Wednesday the president of the European Commission said Britain will regret voting for Brexit and has previously questioned the commitment of Brexit Secretary David Davis to the negotiations. Further criticism came from EU chief negotiator Michel Barnier who said that no "decisive progress" was made on issues like citizens' rights and Britain's financial settlement in the last round of talks in August.
He warned that talks was "quite far" from being ready for EU leaders to authorise the opening of negotiations on the future relationship, which was planned for October.
Downing Street said during the Prime Minister's speech she will give an "update on Brexit negotiations so far" and will "underline the Government's wish for a deep and special partnership with the European Union once the UK leaves the EU".
There is much speculation Mrs May will seek to use the address as an opportunity to make a breakthrough on some of the areas which are blocking progress in talks.
One example of this could be to tackle the EU's demand for payments of £50 billion or more to cover remaining UK liabilities.
The fourth round of formal talks had initially been pencilled in for the week of September 18, but Mrs May's official spokesman denied that the delay was caused by the timing of the PM's speech.
"Both sides settled on the date for that round after discussions between senior officials in recognition that more time would give negotiators flexibility to make further progress," he said.
Explaining her choice of venue, the spokesman said: "The PM wanted to give a speech on the UK's future relationship with Europe in its historical heart.
"The UK has had deep cultural and economic ties spanning centuries with Florence, a city known for its historical trading power.
"As the UK leaves the EU we will retain those close ties. As the Prime Minister has said many times, we are leaving the EU, not Europe."