The Labour leader has refused to give a firm figure on the cost of increased debt from Labour’s proposed £500 billion national investment bank.
But Mr Corbyn insisted in his keynote speech to his party’s conference it would be “foolish” not to borrow to invest at “historically low interest rates”, claiming this will generate “far greater” returns.
He told delegates in Liverpool: “I am not content with accepting second-class broadband, not content with creaking railways, not content with seeing the US and Germany investing in cutting-edge and green technologies while Britain lags behind.
“Last year, for example, the prime minister promised a universal service obligation for 10 megabyte broadband.
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“But since then the Government has done nothing, letting down entrepreneurs, businesses and families, especially in rural areas.
“That’s why we’ve set out proposals for a National Investment Bank, with £500 billion of investment to bring our broadband, our railways, our housing and our energy infrastructure up to scratch.
“A country that doesn’t invest is a country that has given up, that has taken the path of managed decline.
“A Labour government will never accept second best for Britain.”
Shadow chancellor John McDonnell has previously set out plans to borrow billions to support industry as Labour pledged to be an “interventionist” government when it comes to the economy.
But this borrowing would increase the national debt as well as needing huge sums to service it.