Lebanon monitored the brothers accused of plotting to blow up a flight from Sydney to Abu Dhabi for over a year and co-ordinated with the Australian government on it for a long time, the Lebanese interior minister says.

Australian police this month charged Khaled Khayat and Mahmoud Khayat with two counts of planning a terrorist attack after conducting raids to disrupt what authorities described as an Islamic State-inspired plot to bomb an Etihad Airways flight.

Nohad Machnouk told a news conference in Beirut on Monday that one of the men’s brothers, Tareq Khayat, had moved to the IS stronghold of Raqqa in Syria and become a commander in the jihadist group more than a year ago.

Lebanon’s Internal Security Force then placed Tareq, Khaled and Mahmoud Khayat, and a fourth brother Amer Khayat, under surveillance.

Khaled, Mahmoud and Amer were all living in Australia but sometimes visited Lebanon, Mr Machnouk said, adding the brothers were Lebanese.

Mr Machnouk said Amer Khayat had arrived in Lebanon on July 15, the day Australian police have said the plotters tried to smuggle a bomb on to a flight from Sydney to Abu Dhabi.

Australian police had earlier said that a man had tried to check in luggage without knowing that it contained a bomb, hidden in a meat grinder, that his brother had given him.

Mr Machnouk said it was Amer Khayat who was to have carried out the attack and that a Lebanese internal intelligence agency had found he was “involved in the operation”. He said a bomb had also been hidden in a large child’s doll in the luggage.

He did not say what has happened to Amer Khayat.

The plot was foiled because the luggage exceeded the airline’s weight limit, Mr Machnouk said.

Australian police had earlier said that it appeared that one of the accused had left the airport, taking the luggage with him, while his brother boarded the plane and left Australia.

When asked whether the operation would have been successful if the luggage had not exceeded the weight limit, Mr Machnouk said: “Probably, yes.”

He added that information offered by Lebanese intelligence had “assisted in foiling a large operation aiming to blow up a plane”.

“The plane had 120 Lebanese on board in addition to other nationalities,” he said.