The National Observatory of Athens told reporters that the first seismic event occurred at 5:57 a.m. local time and was centered beneath the southern Ionian Sea about 170 miles (270 km) south-southwest of Athens.
It was followed at 2:36 p.m. by a 5.9 magnitude quake that was felt widely across southern Greece, including metropolitan Athens.
National Observatory seismologist Marios Papanikolaou told Agence France Presse that the quakes were probably aftershocks of a strong temblor that hit the same region on February 14.
A 6.5 magnitude quake on June 8 killed two people and injured about 140 others in the northern Peloponnese region from an epicenter just northwest of Saturday's quakes.
