Australian security services have foiled a terrorist plot to bring down an aeroplane with a bomb, Prime Minister Malcolm Turnbull has announced.

Police arrested four people in a series of raids conducted at homes around Sydney.

Turnbull said the suspects were detained “to disrupt and prevent plans to undertake terrorist attacks in Australia”.

It remains unclear as to when and where the attack had been due to be carried out, but it is believed that an Improvised Explosive Device (IED) was the intended weapon.

Members of the Australian Federal Police, New South Wales Police and Australian Security Intelligence Organisation (ASIO) conducted the raids after receiving information about such a device.

“Four men have been taken into custody and are assisting police with their enquiries,” a police statement said.

Turnbull said he had been briefed on the unfolding situation by security organisation heads.

“My number one priority, and that of my government, is the safety and security of all Australians, and the public should be reassured that our security and intelligence agencies are working tirelessly to keep us safe,” the leader said in a statement.