Main opposition SYRIZA-Progressive Alliance leader Stefanos Kasselakis met with former SYRIZA leader and prime minister Alexis Tsipras late Wednesday.
Party sources said that Kasselakis telephoned Tsipras and asked for a meeting in order to "exchange views".
Tsipras agreed and received his successor Kasselakis on Wednesday, at his political office.
The same sources said that Tsipras had the opportunity to express "his concern over the ongoing tension within the main opposition party".
He pointed out the "major importance of SYRIZA-PA's unity so that it can be a reliable main opposition against Mitsotakis' government, as well as ahead of the imminent European Parliament elections".
"It was an overall discussion with a focus on the need for unity in the party," the same sources said.