Police describe twin terror plots, one involving the bombing of a passenger plane and the other a potential poison gas attack, as the “most sophisticated” ever attempted on Australian soil.

A senior ISIS commander sent parts — including weapons-grade explosives — by air cargo from Turkey intending to build an improvised explosive device, Australian Federal Police Deputy Commissioner National Security Michael Phelan said during a press conference Friday.

The other scheme involved a plan to release a toxic gas in public that was foiled when the accused couldn’t produce the deadly gas.

Two men living in Sydney, identified by CNN affiliate Seven News as Khaled Khayat, 49, and Mahmoud Khayat, 32, were charged with terror-related offenses Thursday.

The two appeared by video link Friday in Sydney’s Parramatta Court. No plea has been entered. Neither man applied for bail, and a court hearing has been deferred until November 14 after a brief of evidence was requested.

“At the moment, all I can say is they are entitled to the presumption of innocence,” their legal representative, Michael Coroneos, told CNN affiliate Sky News Australia. “Once the brief of evidence is served, we can assess their legal position.”

One other man remains in police custody, and a fourth has been released.

After the foiled plan to down the plane was revealed Saturday, authorities described it as an Islamist-inspired plot, but they did not link it to a specific terror group until Friday.

Click here to read more.

SOURCE: CNN, Euan McKirdy and Karen Smith