Labor MP Rob Mitchell has written to the Australian Federal Police to request formal investigations into the alleged misuse of parliamentary entitlements by Prime Minister Tony Abbott and Attorney-General George Brandis.

Saying it was "extremely alarming" to see continued reporting of MPs seemingly abusing their taxpayer-funded expense claims, Mr Mitchell urged the AFP to launch an investigation "as a matter of urgency".

The Victorian MP singled out the Prime Minister for what he described as a "systematic" pattern of claims, including about $1700 to attend the weddings of former colleagues Peter Slipper and Sophie Mirabella and billing taxpayers thousands of dollars to compete in a range of sporting events including the Port Macquarie Ironman.