Piraeus, Athens and Peloponnese Railways or SPAP (Greek: Σιδηρόδρομοι Πειραιώς-Αθηνών-Πελοποννήσου "Siderodromi Pireos Athinon Peloponisou" or Σ.Π.Α.Π.

SPAP also acquired the line between Myloi (near Argos) and Kalamata via Tripoli, from the bankrupt Southern Greece Railways (Sidirodromoi Mesimbrinis Ellados).

Short branches were also constructed to serve important towns: Argos-Nafplion, Lefktro-Megalopolis, Kavasila-Vartholomio-Kyllini, Vartholomio-Kyllini Spa (Loutra), Pyrgos to Ancient Olympia, Asprochoma-Messini and, much later (1954), Isthmos-Loutraki.

Passenger services on this branch were suspended in 1957 and it was cut off from the rest of the network in 1962, due to the construction of the Athens-Thessaloniki highway.

Normal levels of service resumed at about 1948 with the exception of the destroyed bridge of Achladokampos (between Argos and Tripoli), which was rebuilt by OSE in 1974.

In 1953 SPAP absorbed Northwestern Greece Railways (SDBE), which operated a metre gauge line from Kryoneri to Messolongi and Agrinion.

[2] The economic crisis in Greece led to the suspension of all passenger and freight services on the metre gauge railway system in the Peloponnese in 2011.