A man claiming to have a bomb in his backpack and accompanied by his young daughter triggered a hostage standoff Tuesday near an Australian court complex, a witness said.

Police said in a statement that it was not known why the man entered the lawyers' offices adjoining the court complex in the western Sydney suburb of Parramatta or what he was "in possession of." Police maintained a cordon around the building, and workers in nearby office blocks said they had been evacuated.

Clerk Betty Hor said she was working at the reception desk at the lawyers' offices when the man approached Tuesday morning and asked to see someone whom Hor had never heard. The man was accompanied by a girl aged about 10 or 11, Hor said.

The man went upstairs briefly then returned to the reception desk and repeated his request. She repeated that she had never heard of the man he was looking for.

Hor said he then threw a book on the desk and told her to call the unknown man and the state attorney-general's department and "tell them I've got a bomb in my backpack."

Hor called police as the man walked upstairs to a lawyer's office with the girl, who called him "Dad."

Hor said he seemed frustrated and angry. She said she had never seen him before.

Television footage showed the man looking from a second-floor window shirtless and wearing the same kind of wig as worn in Australian courts by judges and lawyers. At one stage he spat on the wig.

He later swung a glass bottle like a hammer to smash a plate-sized hole in the office window. He yelled through the hole and threw the bottle then a telephone handset, which was left dangling by its cord.

Five ambulances and two fire trucks were standing by at the scene.

Robert Hoffman, who works in a neighboring office block, said police had evacuated his and other buildings in the vicinity.

Police had moved people at least 100 yards (meters) from the building where the man was holed up, Hoffman said.

The emergency comes a month after an extortionist broke into a Sydney home and fastened a fake bomb around the neck of a millionaire's teenage daughter. She spent 10 terrifying hours with the device strapped to her before police determined it was harmless and freed her.

A man has been arrested in the United States in connection with the crime and is awaiting extradition.