Party critics of Australian Prime Minister Tony Abbott launched a dramatic bid on Friday to unseat the unpopular conservative leader after less than 18 months in office, but he vowed to fight on.

The move comes after Abbott's much-ridiculed decision to award Britain's Prince Philip a knighthood sparked two weeks of turmoil in his Liberal Party, exposing discontent over months of policy failings and plunging poll figures.

"I think we must bring this to a head and test the support of the leadership," West Australian Liberal member of Parliament Luke Simpkins said in an e-mail to colleagues announcing he will initiate a challenge.