Speaking to a conference attended by 350 business leaders in Canary Wharf, London, he said: "I believe that to drive Britain forward, we need a partnership and I'm here to say, Labour is ready, ready to partner with you.

"Because we're not just a pro-business party, we're a party that is proud of being pro-business."

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Sir Keir criticised the Tory governments of the last 12 years for their "failure to seize the opportunities", "short-termism" and "sticking-plaster politics".

He continued: "What I'm focused on is how Labour can remedy that historic wrong because it's going to be our job to tackle the long-term challenges to give Britain a new business model."

Last night, Labour said it will promise to make the UK "the high growth start-up hub of the world".

High-profile figures, including the chair of Tesco and CEO of HSBC, were expected to attend the event.

The event was also due to hear details of the review carried out by independent peer and former Goldman Sachs economist Lord Jim O'Neill into the UK's start-up industry.

The findings of the "Start Up, Scale Up" review include recommendations around removing barriers to institutional investment, helping university innovations get to market and giving more independence to the government-owned British Business Bank.

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Shadow Chancellor Rachel Reeves also gave a speech to business leaders.

She said that Labour wants to see UK pension funds invested in start-ups.

"What I see is a huge pot of money not returning the returns that pension savers in other countries do," she told the conference.

She also vowed to improve trading relationships with the EU as part of her plan for growth.

"We are at a post-Brexit crossroad," she told the conference.

"We can go down the road of managed decline, falling behind our competitors, or we can seize upon the bold thinking that is needed to propel us forward, to shape Britain's future outside the European Union while improving trading relationships with our nearest and closest neighbours, applying ourselves with creativity, with determination and some common sense, so that we can lead the pack in the industries of the future."