Sir Keir Starmer will today tell top Eurocrats that he wants to work 'in lockstep' with them while building a 'more pragmatic and mature relationship'.

The Prime Minister will try to cosy up to European Union bosses with warm words in a bid to 'reset' relations during his first trip to Brussels.

But there could be clashes over a freedom of movement-style deal for young people, with Eurocrats set to warn him that it will likely be the price for closer trading and other ties.

EU officials are also understood to be becoming frustrated with Sir Keir for failing to explicitly say what he wants from a reset - and could demand he spells it out more clearly.

'We need the UK to tell us what it wants,' one diplomat said.

The PM will have talks with Ursula von der Leyen, the European Commission boss, at around 1pm (UK TIME) before meeting EU Council president Charles Michel.

He will round off the day trip by meeting European Parliament president Roberta Metsola at around 4pm.

Before his scheduled departure this morning, Sir Keir, who voted Remain and campaigned for a second referendum in a bid to reverse Brexit while in opposition, said last night: 'The UK is undeniably stronger when it works in lockstep with its closest international partners.

'This has never been more important - with war, conflict and insecurity all knocking on Europe's door.

'We will only be able to tackle these challenges by putting our collective weight behind them, which is why I am so determined to put the Brexit years behind us and establish a more pragmatic and mature relationship with the European Union.

'Better co-operation with the EU will deliver the benefits the British people deserve - securing our borders, keeping us safe and boosting economic growth.'

It strikes a warmer tone than previous Tory premiers, with former PMs Boris Johnson, Liz Truss and Theresa May all having had testy relationships with Brussels during the fraught Brexit negotiations.

Relations thawed somewhat under Rishi Sunak after he struck a new deal on trading relations governing Northern Ireland.

However, Sir Keir's government has repeatedly rejected the EU's proposals for a pact which would allow young people to travel and work in the EU and UK, with Downing Street understood to believe they look too much like the free movement of people ended by Brexit.

EU diplomats have suggested there is only limited room for 'tweaks', meaning the issue of a so-called 'youth mobility deal' could become an early sticking point.

Today's talks will also likely touch on the PM's desire to improve the post-Brexit trade treaty, known as the Trade and Cooperation Agreement (TCA), agreed by former PM Mr Johnson.

This includes striking a 'veterinary agreement' to reduce trade barriers on agrifoods, easier access for service professionals and a deal to reduce paperwork for touring musicians and other artists.

They could also cover greater alignment with the bloc's rules in areas such as the chemicals sector and an enhanced deal for workers in the City of London, which Chancellor Rachel Reeves has previously called for.

Tackling illegal migration and small boat Channel crossings will also be touched on, as well as a potential new security pact and better exchanges between police and security services.

The UK has said that it wants a deal to ease restrictions on touring artists, but the EU has ruled this out.

This is because it would require changes to customs and road haulage rules that breach Britain's own red lines.

During the election campaign, Sir Keir said 'everything' about the 'botched' post-Brexit relationship needed re-negotiating, insisting he could strike a 'better' one.

It sparked fears that he may betray the 2016 vote to Leave by caving into certain Brussels demands and slowly unpicking Brexit, as Eurocrats will expect something in return.

Labour promised in its manifesto, however, not to rejoin the bloc's single market and customs union.

The TCA is scheduled to be formally reviewed in 2026, when tensions over other traditionally emotive issues - such as fishing rights - could resurface.

France has told other EU countries that any 'reset' with the UK must include the same level of fishing access to Britain's waters as at present.