Ukrainian leader Volodymyr Zelensky has told outgoing UK prime minister Sir Keir Starmer that he will always be a 'welcome guest in Ukraine' following his bombshell resignation this afternoon. 

Following months of worsening polls, Starmer this afternoon tearfully announced he would be stepping down as leader of the UK. 

The PM talked up his achievements in getting Labour elected - as well as making a series of dubious claims about successes in Government - in a statement outside the famous black door of 10 Downing Street. 

But he acknowledged that his time had run out. 'I know the question being asked now is not who is best placed to change the Labour Party... the question my party is asking now is whether I am best placed to lead us into the next general election.'

He added: 'I accept that answer with good grace... that is why I will resign as leader of the Labour Party.' 

Following his resignation, Zelensky profusely thanked Starmer for his work to assist Ukraine in its fight against the Russian invasion. 

Zelensky wrote in a social media post: 'Keir, thank you for all our cooperation, your support, and the joint decisions that have helped make our Europe and our protection of life stronger. 

'The United Kingdom has been, is, and will remain among the world's leaders. Here in Ukraine, we deeply value Britain, and every meeting and every conversation we have had has always been filled with real substance. 

'Thank you for always being in touch, always engaged, and always striving to do what is needed and what will truly help. I wish the United Kingdom and all British people every success as well as realisation of your national goals. 

'We have confidence in Britain. Keir, you are always a welcome guest in Ukraine.' 

Following Starmer's announcement, the Kremlin weighed in. 

It said his resignation was unlikely to change what it characterised as London's hostile attitude towards Russia.

Starmer said on Monday he would resign, promising to ensure an orderly transfer of power to a new leader by September at the latest to try to avoid political instability as Britain prepares for its seventh leader in 10 years.

'Starmer has not done anything to distinguish himself on the issue of British-Russian relations,' Kremlin spokesman Dmitry Peskov told reporters.

'He has always been in favour of keeping relations at a zero level. It is unlikely that anyone on the British political scene will hold a position on our country that differs from Starmer's,' said Peskov.

Just a week before he resigned, Starmer pledged to send £210 million to Zelensky's nation to help it build nuclear plants which he said would 'power Ukraine through the winters ahead.'

He said following the announcement, which also revealed a spate of new sanctions against Russia: 'We will stand with Ukraine for as long as it takes and this announcement reinforces that.

'Putin should roll back his tanks, end his barbaric strikes and come to the negotiating table.'

EU Commission Ursula von der Leyen praised Starmer following his resignation. 

Writing on X, she said: ' It can take many leaders years to grow into the statesman you became in just two years. 

'European and Ukrainian security is stronger because of you. Thank you, dear Keir.' 

Starmer said there would be an 'orderly' process to choose his replacement. He said a successor would be in place before the Commons summer recess on July 16 if there is only one candidate - Andy Burnham. Otherwise the decision could take until August.

However, Starmer became emotional as he paid tribute to the support from his family - saying he would now focus on being the 'best husband' and the 'best dad'. 

Wife Victoria and the couple's son had joined close colleagues outside in the street to watch the news being delivered.  

Burnham - who has rallied huge support from Labour MPs since romping home in the Makerfield by-election last week - is due to be sworn in at the Commons at 2.30pm. The pair are not thought to have spoken directly for months. 

Nigel Farage immediately joined calls - including from some Labour MPs - for a general election to accompany the change at the top. 

The PM returned to Downing Street from Chequers early this morning, after spending the weekend locked in talks with wife Victoria and close aides. He spoke to the King, who is at his Highgrove residence, by phone before making the announcement.