The lead singer of US soul pioneers the Isley Brothers, Ronald Isley, has been sentenced to three years and one month in prison for tax evasion.

Isley was also ordered to pay $3.1 million in back taxes to the US taxman in recompense for what was described as his 'pathological tax evasion'.

Pleading leniency, his lawyer cited Isley's recent complications from a stroke, his fight with kidney cancer, and the death of two of his accountants, all of which hindered his record keeping during the years that led to the criminal charges.

But despite Isley's attempts at paying off his IRS debt, US District Judge Dean Pregerson handed down a full sentence. 'The term serial tax avoider has been used. I think that's appropriate,' said Pregerson.

The 64-year-old Isley had reportedly been cashing in royalty cheques in the name of his late brother O'Kelly, and spending the income from undeclared live performances worth millions on a yacht and two homes.

The Isley Brothers were a highly popular vocal group between the '50s and late '70s.

Ronald's wife is expecting a baby early next year.