British Prime Minister Theresa May will make two speeches on Brexit in the coming weeks to provide more details setting out the country's path to leaving the European Union.

Britain is hoping to seal a transition deal next month to smooth its exit from the EU, and reach agreement on a long-term trade agreement later this year.

However, Brussels said last week a transition deal was not a certainty and that London needed to clarify what it wanted from the EU.

Mrs May's government will aim to address that in a series of six speeches by the prime minister and other senior ministers in the next few weeks, which her office dubbed "The Road to Brexit".

"Brexit is a defining moment in the history of our nation," a source in Mrs May's office said.

"As we move along the road to that future, we will set out more detail so people can see how this new relationship will benefit communities in every part of our country.

Mrs May's first speech, to be delivered at a conference in Munich next Saturday, will set out the security relationship Britain wants with the EU.

She will deliver another setting out Britain's future partnership, although a date for that has yet to be confirmed.

The country’s foreign minister Boris Johnson, a leading Brexit advocate, will begin the 'Road to Brexit' series with a speech on Wednesday, described by Mrs May's office as a "rallying cry to those on both sides of the Brexit debate."

UK Brexit minister David Davis will outline how Britain’s businesses can maintain their global reputation after Brexit in an as yet unscheduled speech.

Trade minister Liam Fox and cabinet minister David Lidington will also give speeches.

Britain's finance minister Philip Hammond, seen as the most pro-EU member of Mrs May's cabinet, will not give a speech.