SIR Keir Starmer has been warned not to unpick Brexit when he holds a big Eurofest at a swanky stately home.
The new Prime Minister will host nearly 50 European leaders at Blenheim Palace, the birthplace of Winston Churchill.
He plans to discuss migration, energy and democracy at the mega summit in Oxfordshire on Thursday.
But MPs fear the new PM will water down the Brexit agreement in his bid to bring the UK closer to the EU.
“He should sup with a long spoon,” former Tory leader Sir Iain Duncan Smith said.
“We have left the EU and he pledged not to reverse it. They will want their pound of flesh for any new arrangements and that will look like entry through the back door. Beware the Greeks bearing gifts.”
Tory MP Alec Shebrooke added: “The man who tried to undo Brexit and have a second referendum is now hosting European leaders clearly with the intention – as he has said – of closer integration.
“That means we will be the rule takers with no seat at the table.”
The Prime Minister has insisted the UK will not rejoin either the EU, the single market or the customs union within his lifetime.
Sir Keir said: “Europe is at the forefront of some of the greatest challenges of our time.
“Russia’s barbaric war continues to reverberate across our continent, while vile smuggling gangs traffic innocent people on perilous journeys that too often end in tragedy.
“We cannot be spectators in this chapter of history. We must do more and go further, not just for the courageous Ukrainians on the frontlines, or those being trafficked from country-to-country, but so our future generations look back with pride at what our continent achieved together.
“I said I would change the way the UK engages with our European partners, working collaboratively to drive forward progress on these generational challenges, and that work starts at the European Political Community meeting on Thursday.”
The European Political Community meeting will be Sir Keir’s first major UK-led summit of his premiership.
He will meet French President Emmanuel Macron for a dinner after the summit, and Irish Taoiseach Simon Harris beforehand.