A blown rail joint has damaged track at Slade Green cancelling all Southeastern trains today on the Woolwich line.
The issue affects Kent-bound trains and not those running towards London.
The issue was originally expected to be resolved by midday, though further investigation by Network Rail shows work will now need to be undertaken overnight.
The issue compounds existing cuts announced by Thameslink who suspended all services on the line this week owing to staffing levels.
In addition delays are occurring after problems after engineering work in the Lewisham area over Christmas.