Bernie Sanders and his wife made more than $1 million in both 2016 and 2017, newly released tax returns have revealed, shining a light on the wealth of the Left-wing presidential hopeful.

Mr Sanders, a self-proclaimed democratic socialist who sits as an independent in the US Senate, enjoyed the surge of income in part thanks to books he has written about politics.

The 77-year-old released 10 years of tax returns on Monday, following similar moves by rivals who are also seeking the Democratic Party’s 2020 presidential nomination.

The revelation is politically challenging for Mr Sanders given he has railed against the “millionaires and billionaires” and their influence over the political system.

Mr Sanders said in a statement: “These tax returns show that our family has been fortunate. I am very grateful for that, as I grew up in a family that lived paycheck to paycheck and I know the stress of economic insecurity.”