Independent Greeks (ANEL) party leader Panos Kammenos, a former partner of SYRIZA in a ruling coalition, expelled deputy Thanassis Papachristopoulos from the party's parliamentary group, a party statement said on Friday.
The decision effectively dissolves the parliamentary group of ANEL, since rules stipulate that a party needs to have at least five deputies in parliament.
Papachristopoulos, who voted against party lines by supporting the Prespes Agreement, had said he would resign his seat but did not do so. He is now considered independent.
Plenary discussion is continuing in parliament on ratifying the accession protocol for the Former Yugoslav Republic of Macedonia to join NATO under its new name of "Republic of North Macedonia".