Tony Abbott broke with tradition and skipped an annual black tie dinner held for government senators when he attended a party fund-raiser in Melbourne on Monday night.

The trip has caused a stir after the Prime Minister admitted to colleagues he made an early morning visit to a cancer research centre on Tuesday so he could justify the interstate visit under entitlements.

Prime Minister Tony Abbott. Credit:Andrew Meares

The visit ran over time and caused Mr Abbott to arrive one hour late to a regular meeting of Coalition MPs.

He was taken to task by government senator Ian Macdonald, who was swiftly rebuked by a colleague. But the confrontation elicited Mr Abbott's frank confession about scheduling an official visit the morning after his fund-raiser so he could bill taxpayers for the travel.