BOMB disposal experts have issued a warning after an aircraft rocket was handed in to a police station.
The man took the 28lb two-foot rocket to Middlesbrough Police Station because he had seen children playing with it.
More than 100 officers and prisoners, as well as the neighbouring magistrates' court, library and residents, had to be evacuated.
It turned out to be a dummy, but the Army said that moving a live bomb could detonate it, potentially killing or maiming people.
Army spokesman John Salisbury-Baker said it was impossible to say where hand grenades, anti-aircraft missiles, unexploded bombs and mines left over from the two world wars could turn up.
He said: "They can crop up in ornamental flower beds and only be unearthed after a heavy rainfall when the topsoil is moved. It is surprising where things end up.
"The police and bomb squad would rather people contacted them rather than risk setting it off.
"It does not matter if they end up being duds, they are not going to be angry. It is better being careful than being dead."
Mr Salisbury-Baker said the Army only tested their weapons on sites away from public areas and that records are taken of what ammunition is used.
He said: "Today we are very careful and we know what we are using and whether something has gone missing, but 60 years ago, during the fog of war, we might not have been so careful.
"From time to time, we get very big ones that failed to go off during the German bombing raids that will be washed up on the seashore."
The same caution should be adopted when members of the public find suspicious packages in public places because of the threat of terrorism.
Sergeant John Blake, of Cleveland Police, supported the Army's advice. He said: "The public should be extra vigilant during these times where there is a heightened terrorist threat.
"There is no need to panic, but it is something we should all be aware of, and people should stay alert."
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