An employment expert's raising his eyebrows over Xero investigating complaints against the newly crowned New Zealander of the Year.

The tech company's reviewing a decade-old accusation of inappropriate behaviour from former chief executive Sir Rod Drury - which has come to light, and he denies.

Employment relations specialist Max Whitehead says Xero can't do much.

"It's a mystery why Xero are taking any action, there's a 90-day limit on taking a personal grievance. The other thing is that maybe the Human Rights commission - but there's a 12-month limit on that." 

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• Xero launches misconduct probe into former boss and New Zealander of the Year