Deputy Nationals leader Bridget McKenzie charged taxpayers thousands of dollars to attend an awards night for shooting in Sydney, claiming the trip as "electorate business" even though she was a Victorian backbencher.

Senator McKenzie has now sought to justify the travel because of her role as chair of the Parliamentary Friends of Shooting group – but parliamentary friendship groups are informal bodies that do not come with any public spending entitlements.

Deputy Prime Minister Barnaby Joyce congratulates the Nationals deputy leader Bridget McKenzie last week. Credit:Nick Moir

The Nationals MP – elected last week as Barnaby Joyce's deputy, replacing Fiona Nash – charged the public purse $2279.67 for the overnight trip from Melbourne to Sydney for the Shooting Australia Awards of Excellence in February this year.

Senator McKenzie charged $1611.12 for business class flights, $268.55 for official cars and $400 for her overnight travel allowance. On her publicly available travel expense paperwork, she classed the trip as "electorate business".