Keir Starmer has dodged the local election campaign trail to embark on a 4,500-mile round trip to the Armenian capital Yerevan for a meeting aimed at bringing Britain closer to the European Union.

The PM – who critics have branded 'Never Here Keir' over his love of foreign jaunts – hoped to hold talks about deepening ties with the EU as well as taking part in discussions on Ukraine.

He has been drawing up plans for a major push to align with EU rules in a shift to the Left designed to head off a leadership challenge following local elections this week that are expected to be disastrous for Labour.

The Prime Minister has vowed to take Britain 'much closer' to Brussels – as Labour members push him to rejoin the EU. Sir Keir signalled his move in a series of interventions over the weekend in which he ramped up his anti-Brexit rhetoric.

In Yerevan he'll join a meeting of the European Political Community (EPC), made up of EU member states and neighbouring countries but which has no decision-making powers.

The PM, who was bitterly opposed to Brexit, tried to neutralise the issue at the last election by promising not to revisit the result of the 2016 referendum.

But he told the BBC over the weekend that he now believes Britain needs to be 'much closer' to the EU.

Writing in the Observer newspaper, he claimed that strengthening the economy 'means deepening our economic relationship with the EU'.

He added: 'The world has changed since 2016. And Brexit today looks quite different. It has damaged our economy and there's no doubt in my mind where the national interest lies. Britain must be at the heart of a stronger Europe on defence, on security, on energy, and on our economy.'

In a further statement of intent, Sir Keir said Britain would contribute to EU plans for a £78billion loan to Ukraine. Sources have previously suggested the UK's share could be around £2billion.

At the meeting, the PM pledged to intensify work on a new defence pact with the EU.

'When the UK and the European Union work together, we all reap the benefits,' he said. 'And in these volatile times we need to go further and faster on defence to keep people safe.

'That is why we are beginning negotiations with the EU to ensure Ukraine gets the equipment it needs to defend its freedom, while driving opportunities for British industry to play its full part.'

Any push for closer alignment would require Britain to follow EU rules over which it no longer has a say.

Whitehall sources acknowledge that the price of greater access to the single market is likely to involve contributing billions of pounds a year to the EU budget to pay for 'social cohesion' projects such as new bridges in poorer EU states.

The PM's comments came as a new poll of Labour members revealed overwhelming support for rejoining the EU, despite the outcome of the Brexit referendum.

The Survation poll for the website LabourList found that activists support rejoining the bloc Britain left a decade ago by a margin of 87 per cent to 9 per cent. 

The survey revealed that Labour members would support rejoining the EU even if it means scrapping the pound and joining the euro, although the margin of support falls to 53-30.

Labour's London mayor Sir Sadiq Khan said in March that Labour should fight the next election on a manifesto pledge to rejoin the EU, arguing that it was 'inevitable'. 

The new survey found that Labour members backed the idea of a manifesto pledge by a margin of 65-24.

Shadow Foreign Secretary Dame Priti Patel warned that Britain would pay a heavy price if Sir Keir moves to rejoin the EU in order to head off a Labour mutiny. She told the Daily Mail: 'Starmer is trying to unpick Brexit at every opportunity he can.

'The Conservatives have set out five tests to stop Labour dragging Britain back into the EU's orbit, including stopping Labour from handing over taxpayers' money to European institutions, with no end date and no democratic mandate. Every negotiation Starmer enters results in a bad deal for Britain.

'This follows his damaging attempt to give away the Chagos Islands for £35billion and only last week he handed over half a billion pounds to the French. 

At every turn, this weak Prime Minister goes to the negotiating table and comes home empty-handed, having fleeced hard-pressed taxpayers for his appalling lack of judgment.'

But the PM's allies believe that cosying up to Brussels could be a trump card in his strategy to head off a leadership coup. 

Rivals such as Andy Burnham, Wes Streeting and Angela Rayner are all expected to use any leadership contest to push for much closer relations with the EU, in line with the views of party members.

Sir Keir believes he can own the issue himself and is already planning a major summit with European Commission chief Ursula von der Leyen next month where he is expected to push for a deal that goes far beyond Labour's manifesto pledge of a modest 'reset' focused on food and farming.