UK's Labour Party leader Keir Starmer has criticized the Conservative leadership candidates over their tax proposals, accusing them of having "just arrived from the moon." 

Foreign Secretary Liz Truss is the latest big name to enter the race to replace the outgoing Boris Johnson, pledging to start cutting taxes "from day one."

Starmer outlined his party's priorities on Monday, stating his determination to give the UK "the fresh start it needs."

Concerning the battle to become the next UK Prime Minister, Starmer said: "I cannot believe what we are hearing from the candidates to be the next Tory leader. The Tory leadership race hasn't even officially begun yet, but the arms race of fantasy economics is well underway. 

"Over the weekend, the contenders have made more than £200bn ($238bn) worth of unfunded spending commitments. Let that sink in. That's more than the annual budget of the National Health Service, splurged onto the pages of the Sunday papers, without a word on how it'll be paid for.

"And on taxes, the vast majority of them served in Boris Johnson's government. They went out every day for months and years to defend his behaviour. They're behaving like they've just arrived from the moon. They nodded along and trooped through the voting lobbies to support them. Now, it turns out they were opposed to them all along. The hypocrisy is nauseating."

Starmer claimed Britain was "stuck" with a  "tanking economy", with taxes going up and food and energy bills  "out of control."

"Only Labour can reboot our economy and end the cost-of-living crisis," he added.  "Only Labour can revitalise our public services and re-energise our communities. Only Labour can unite the country and clean up politics. 

"These three tasks will define my government. Because until we address them, we leave ourselves vulnerable to the shocks and crises we have endured this past, long decade. Yet the way I see it, the challenges we face – climate change, technology, an ageing population – are an opportunity to re-energise Britain."