A man planned to drop a homemade pipe bomb in Sydney Harbour because he was having a bad day, police allege.
A man was arrested at Lidcombe train station in Sydney's west on Wednesday night, after a 10-centimetre bomb was found in his pocket.
Inspector Barry Vincent said police suspect the man was "intending to travel into the city where he intended on detonating it within a body of water".
Police allege the man told officers he was not targeting any particular business or person, just taking the bomb into the city because he was having a bad day.
It would not have caused widespread damage, Insp Vincent added.
"Certainly, in the harbour, I wouldn't expect there would be too much damage, if at all...
"The fact he's got it with him was a concern but there was no intention to target any person or location.
"We will be alleging that (the man) made reference that he had a bad day," Insp Vincent said.
It was not known why he was upset, Insp Vincent said.
Police say the man became agitated on a busy railway platform at 7.40pm (AEDT) on Wednesday when he saw officers with drug-detection dogs.
During a search, officers allegedly found a pipebomb in a glasses case in his pocket.
The Rescue and Bomb disposal unit was called and took the bomb to a safe location and detonated it.
A subsequent search of the man's home allegedly turned up a firearm, ammunition, a spear gun and a quantity of a white substance, believed to be methamphetamines.
A 33-year-old Chester Hill man is due to appear in Burwood Local Court on Thursday, charged with possessing an explosive in a public place, possessing a knife and other transport offences.
No comment was made to ID the guy , therefore we assume from previous cases he middle eastern or of that flavour ...
this makes the 5th caught bomber in 2 months .. all middle eastern or flavoured that way