Trains between Great Victoria Street and Lisburn are closed on Friday morning after a "tragic incident".
Disruption is expected on February 18 until further notice.
A Translink spokesperson said: "Due to a tragic incident at Adelaide Halt, the train line between Great Victoria Street and Lisburn is closed.
"See link for the latest information on your service."
The website added: "Due to an operating incident between Great Victoria Street and Lisburn the line is closed.
"Train services running through these stations may be cancelled, delayed or revised. Disruption is expected until further notice."
A PSNI spokesperson said: "Police are at the scene of an incident at Adelaide Halt in Belfast. The train line has been closed and is expected to remain closed for some time. There are no further details at present."
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