Australia terror probe: Two men charged over 'plot to bomb plane'

The raids on properties in Sydney provided "very strong" evidence against the suspects, police said

Two men have been charged with terrorism offences in Australia over a suspected plot to bring down an aircraft.

Police said an alleged plan to blow up a plane was thwarted following a number of raids conducted at the weekend.

Four suspects were arrested in Sydney on Saturday accused of planning an attack using an improvised explosive device (IED). One man was released on Tuesday and another remains in custody.

Security was later raised at airports.

Investigators have been gathering evidence in what Prime Minister Malcolm Turnbull called a "major counter-terrorism operation".

The raids on the properties in Sydney provided "very strong" evidence against the two suspects, New South Wales Police Commissioner Mick Fuller said on Thursday.

Passengers have had to wait in lengthy queues after Australia's airports raised security measures

The two men, aged 32 and 49, were each charged with two counts of "acts done in preparation for, or planning, a terrorist act", the Australian Federal Police said.

The charges carry a maximum sentence of life imprisonment. The men are due to appear in a Sydney court on Friday.

Police have until the weekend to hold the fourth man without charge after obtaining a court extension.

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Australia's terror threat

Following the latest alleged terror plot, Australia's airports increased their security measures, leaving passengers waiting in lengthy queues after being advised to arrive earlier than usual.

On Thursday, Mr Turnbull said that the raised security measures were "constantly under review".

Australia's national terror alert level was raised to high in September 2014 amid concerns over attacks by individuals inspired by organisations such as so-called Islamic State (IS).

• Australia's home-grown terror threat

Dozens of Australians are thought to have joined IS militants in Iraq and Syria in recent years and the Australian government has implemented new national security laws in response.

Experts have raised concerns about the effect of returnees - and those who support them - on security.