Theresa May will underline the UK's continued commitment to European security after Brexit as she travels to Brussels to boost progress on deadlocked negotiations.

The Prime Minister will hold fresh talks with European Council President Donald Tusk at a summit with Eastern European nations on Friday amid reports she is preparing to offer some £40bn to the EU to open up trade talks next month.

EU officials reportedly described the meeting as a bid to agree the "choreography" of a deal, which must be agreed before the European Council summit next month to allow discussions to move on to future trade relations.

The EU has refused to discuss trade and transition arrangements until sufficient progress is made on issues of Northern Ireland, citizens’ rights and the "so-called" divorce bill - with Mr Tusk demanding greater clarity from the UK before moving forward.

Irish premier Leo Varadkar also said Dublin would try to block EU trade talks unless it received a written guarantee that there would be no return to a "hard border" between Northern Ireland and the Republic.

Ms May is understood to have secured the backing of the Cabinet to double the amount offered to the EU to around £40bn but she agreed with ministers that the extra cash must be conditional on what kind of trade deal is available.

The Prime Minister's official spokesman played down suggestions that she was meeting Mr Tusk to set out the divorce bill.

He said: "They will be discussing progress towards the December council.

"There are a number of issues which I'm sure they will want to discuss - the financial settlement, that will be one of them, also of course Northern Ireland and citizens' rights."

It comes as a leaked diplomatic dossier said internal Tory "chaos" was undermining Brexit talks, with particular criticism aimed at both Brexit Secretary David Davis and Boris Johnson, the Foreign Secretary.

On her visit to Brussels, Ms May will tell Eastern European leaders that the UK is "unconditionally committed" to European security in the face of growing threats from Russia.

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She will say: “From agriculture in Ukraine to the tech sector in Belarus – there is a huge amount of potential in the Eastern neighbourhood that we should nurture and develop.

“But we must also be open-eyed to the actions of hostile states like Russia which threaten this potential and attempt to tear our collective strength apart.

“This summit highlights the crucial importance of the European countries working together to protect our shared values and ideals.