Trains are running again between Sutherland and Cronulla/
Sydney Trains said services were returning to timetabled schedule after urgent track equipment repairs at Sutherland earlier in the day.
Buses are replacing trains in both directions between Sutherland and Cronulla while track repairs are carried out.
Delays affect the entire T4 - Eastern Suburbs & Illawarra Line
Sydney Trains advised earlier the Cronulla line had reopened.
However, at midday the line remained closed.
Buses are also supplementing some trains on the South Coast Line between Port Kembla and Wollongong.
Sydney Trains said passengers should allow plenty of extra travel time, listen to announcements and check indicator boards
Train services have resumed between Sutherland and Cronulla but long delays continue.
Continue allowing plenty of extra travel time in both directions due to urgent signal equipment repairs at Sutherland.— T4 Sydney Trains (@T4SydneyTrains) May 15, 2017
Sydney Trains said: “Trains are suspended between Sutherland and Cronulla in that direction only. Buses are being arranged to operate a replacement service”.
At least one Bondi Junction to Sutherland service was terminated at Mortdale due to signal equipment repairs at Sutherland.
Earlier, Sydney Trains said in a statement:
“Customers are advised that trains are being delayed on the T4 - Eastern Suburbs & Illawarra Line in both directions due to urgent track equipment repairs at Sutherland.
“Bus companies are being contacted. Delays can be expected.”