Sir Keir Starmer will be accompanying Ukrainian president Volodymyr Zelenskyy to Washington

Sir Keir Starmer will be accompanying Ukrainian president Volodymyr Zelenskyy to Washington tomorrow for his crunch meeting with Donald Trump.

He will join European leaders including France's president Emmanuel Macron, Italy's PM Giorgia Meloni and Germany's Chancellor Friedrich Merz after the US president reportedly extended an invitation to them.

Also set to attend the talk at the White House are NATO Secretary General Mark Rutte and Ursula von der Leyen, the president of the European Commission.

Read more: Why is Zelenskyy bringing a posse of leaders?

This comes after Vladimir Putin reportedly made demands to take control of the key eastern Donetsk and Luhansk regions of Ukraine during his summit with Mr Trump as a condition for ending the war.

In exchange, Mr Putin would give up other Ukrainian territories held by his troops, according to several news reports citing sources close to the matter.

Mr Trump is said to be planning to urge Mr Zelenskyy to agree to the conditions as part of a peace deal to end the war, despite the Ukrainian president previously ruling out formally handing any territory to Moscow, as such a move would deprive Ukraine of defensive lines and open the way for Moscow to conduct further offensives.

Russia already controls a fifth of Ukraine, including about three-quarters of Donetsk province, which it first entered in 2014.

Read more: The territory Ukraine could be told to surrender

European leaders who make up the "coalition of the willing" are set to hold a conference call today ahead of the crunch talks between Mr Trump and Mr Zelenskyy, which some coalition members are set to attend.

They are expected to discuss how to bring Mr Zelenskyy into talks after Mr Trump and Mr Putin's meeting saw him left out in the cold.

In coordinated statements following the Alaska summit, European leaders said Mr Zelenskyy must play a greater role in future talks, and that peace cannot be achieved without him.

The US president said the Washington talk with Mr Zelenskyy could potentially pave the way for a three-way meeting with Mr Putin.

Read more from Sky News:Analysis: Zelenskyy knows he risks another ambushBody language expert unpacks Alaska summit

On Saturday, Downing Street insisted Sir Keir and other allies stand ready to support the next phase of talks to end the war.

"At the meeting that will take place at the White House tomorrow, the Prime Minister, with other European partners, stands ready to support this next phase of further talks and will reaffirm that his backing for Ukraine will continue as long as it takes," a statement from No 10 said.