RAIL passengers from Hull were delayed after an old hand grenade was found on the track.
The explosive was discovered on the line between Garforth and Cross Gates, near Leeds, at 1.33pm yesterday.
Police cordoned off the scene within minutes, before specialist military officers – commonly known as the "bomb squad" – investigated the device.
They later deemed the grenade to be safe.
A British Transport Police spokesman said: "Officers were called to Marsh Lane railway sidings, close to Leeds station, after the discovery of what is believed to be an old hand grenade.
"They attended alongside colleagues from West Yorkshire Police and cordons were put in place.
"The grenade was inspected by specialist military officers, who deemed the device to be safe.
"No members of the public were in any danger during the incident and there is no suggestion of any criminal activity."
Trains between Leeds, York, Selby and Hull were diverted, with commuters forced to use replacement bus services.
However, services were running as normal within an hour.
A First TransPennine Express spokesman said: "The longest delays people had to deal with were about half an hour.
"The lines were reopened at 2.30pm, with the trains back on timetable.
"We kept the replacement buses between Leeds and Hull on standby throughout the afternoon, just in case there were further problems."
Speculation on social-networking sites was rife, with some Twitter users reporting the grenade was an "unexploded" device.
Others commented on the train conductors' brutal honesty, with one Leeds man Tweeting: "Conductor at Leeds station: sorry about the delay, signals are down due to a hand grenade being found just outside the station #feelingsafe."
The British Transport Police are investigating how the grenade came to be on the tracks.
A spokesman said: "We would urge anyone with information to call the British Transport Police on 0800 405040, quoting incident reference 263 of Wednesday, June 5."
