TYNE and Wear Metro bosses have warned youngsters against trespassing on the system.
The message has been reinforced by advertising hoardings with the message: "We will not forgive those who trespass against us."
Managers at Nexus, the system operator, said they had a stringent policy of prosecuting trespassers.
Legal chiefs who supervise prosecutions are warning potential trespassers to steer clear, or face fines of up to £1,000.
High on the agenda were youngsters who, during the school summer holidays, might put their lives at risk by playing near the Metro tracks.
Trespassers also risked the possibility of electrocution, or being hit by trains
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