Disquiet over Australia’s military fight against Islamic State (IS) has emerged within the Labor Opposition.

Opposition Leader Bill Shorten has fully backed the deployment of 600 Australian personnel and fighter jets to the Middle East, but West Australian Labor backbencher Melissa Parke says she holds concerns.

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Ms Parke says like her leader, she is horrified by the recent execution of a British hostage by IS militants, but is concerned at Australia’s response.

“As a former aid worker myself, I am horrified by the brutal killing of David Haines, a person only trying to do good in the world,” she told the ABC.

“However, I am very concerned that the Government has so quickly escalated Australia’s involvement in Iraq from strictly humanitarian protection to now committing Australia to what appears to be an open-ended war that will only increase the security threat to Australians.”

The Federal Member for Fremantle says the security threat is one which has already been heightened by Australia’s involvement in the 2003 Iraq “debacle”.

The former human rights lawyer is demanding Prime Minister Tony Abbott bring the matter on for a full debate in Federal Parliament.

Earlier this month the Government and Labor rejected a Greens push demanding Parliament be given the responsibility of authorising military deployments, as do the US and UK legislatures.