A SCRAP of paper found at a home raided in connection with a Sydney terror plot could give police more information about the plan a would-be terror team had to bring down a flight.

The small piece of evidence was found in a wheelie bin outside the Lakemba home raided by police over the weekend over the suspected terror plot by four men to bomb a plane departing Australia, possibly using a meat mincer.

While searching the address on Monday, police uncovered a flight release slip, which featured a flight code for a Jakarta to Sydney route inside a wheelie bin outside the home the Daily Telegraph reports.

According to the Telegraph, a letter addressed to another property that was raided was also collected as evidence by police.

The Lakemba property was one of five raided in suburbs across Sydney over the weekend in connected to what authorities have described as a “very sophisticated plot”.

A pair of father and son would-be terror teams were arrested on Saturday afternoon over the alleged plot, and will remain in detention for up to a week as police comb through evidence.

The four men’s plan was thwarted when authorities picked up a “small piece of intelligence” about the possible plot to smuggle an improvised explosive device onto an international flight bound for the Middle East. Authorities say the plot was “Islamist inspired”.

The Daily Telegraph has reported the bomb may have been disguised as a kitchen meat grinder, that was to be carried in hand luggage onto a flight departing Sydney.

Other media reports suggested it could have been a “non-traditional” device that would have distributed poisonous gas within the plane.

A kitchen device used to make sausages was among items seized in raids in five separate homes across Sydney over the weekend. Mobile phones and documents were also taken from the properties.

Police decided to arrest the men on Saturday after a period of surveillance, deciding the risk to public safety was high.

Authorities have declined to comment on whether Austrailan intelligence was tipped of by authorities overseas bevore they arrested the men.

NSW Police and AFP officers swooped on five properties in the suburbs of Surry Hills, Lakemba, Wiley Park and Punchbowl on Saturday afternoon.

The four arrested, believed to be two groups of father and son, linked by marriage, are being held by AFP for an additional period of detention.

The men had previously been unknown to police and security agencies.

Speaking with ABC radio on Monday, Justice Minister Michael Keenan said authorities had uncovered what appeared to be a “very sophisticated plot” and would have taken “extensive planning”.

A magistrate granted an extension, allowing authorities to hold the men for up to seven days while a complex investigation continues.

The thwarted plan has affected travel all around Australia, with authorities enforcing extra security measures following the threat.

Travellers have been warned to arrive two hours before their domestic flight because of “additional scrutiny”.

Those flying internationally will need to arrive three hours before their flight is scheduled, with security experts expecting the arrangements will be in place for the foreseeable future.

Prime Minister Malcolm Turnbull said the threat of terror in Australia was “very real”.

NSW Police Commissioner Mick Fuller said police had to act when they did.

“With terrorism you can’t wait, you can’t wait to put the whole puzzle together, you do have to go early because if you get it wrong the consequences are severe,” he said.

“You need to make the decision at some stage, when is the right time to go. Both (Australian Federal Police) and NSW Police agreed last night was the right time to go.”

AFP Commissioner Andrew Colvin confirmed the threat involved an improvised device and was Islamist inspired.

“We’ve taken this threat very seriously,” he said on Sunday.

“You should infer that we think this was credible and there was an intention, and there was quite possibly a capability as well.”

Speaking on Monday, Mr Colvin would not specify whether the would-be terrorists had planned to blow up an international or a domestic flight, saying the threat was “non specific”.

He said extra security measures were being enforced at both airports.

“Australians should be very confident in the security apparatuses that we have at our airports,” he said. “What we are doing, and what you’re seeing now, is making sure there is extra vigilance.”

Prime Minister Turnbull said airport security measures had been increased for public safety.

“The tight co-operation and collaboration between our intelligence and security agencies is the key to keeping Australians safe from terrorism,” he said.

Travellers were warned to expect delays and increased scrutiny at all Australian departure points after security measures were “intensified”. “Some of that will be visible, some of it will not be visible, but it will take more time,” Mr Turnbull said.

In Surry Hills and Lakemba, where the men were arrested, neighbours have expressed shock.

“Never in my life would I have expected this ... they’re a very nice family,” one Surry Hills neighbour said.