Train services across Ipswich were facing delays due to a trespasser on the tracks.
All lines to Felixstowe, Lowestoft and Stowmarket were blocked, with disruption expected until 10.30am.
Police were at the scene and the lines will stay closed until the trespasser and railway staff are safely clear.
A spokesman for British Transport Police said: "We were called at around 8.50am today (15 September) to reports of a trespasser on the tracks near Ipswich railway station.
"Following a thorough search of the area, no one was found."
The incident was disrupting intercity trains between London Liverpool Street and Norwich, plus services from Ipswich to Felixstowe, Lowestoft and Cambridge.
Trains to and from Norwich, Cambridge, Lowestoft and Felixstowe cannot arrive at or leave Ipswich.
Services between London Liverpool Street and Ipswich are still running.
Greater Anglia had warned passengers to expect delays and consider alternative travel, however the disruption has now ended.
Passengers with advance tickets could use them on an earlier or later train if their booked service is cancelled.
Trespassing on the railway is illegal and can lead to a £1,000 fine.
See the Network Rail website for more information.
Greater Anglia and Network Rail have apologised for the disruption.
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