A Greek prosecutor on Saturday ordered an investigation into alleged threats to lawmakers over a name deal with Greece's neighbour Macedonia, a judicial source said.
Macedonia's parliament on Friday passed an amendment to the constitution to rename the country Republic of North Macedonia, in line with an agreement with Greece to put an end to a 27-year-old dispute.
Many Greeks are irked that their Balkan neighbour is assuming a name linked to Greek heritage and identical to a northern region of Greece.
The countries struck the deal in June, but Macedonia will start using the new name only after the parliament in Athens also ratifies the agreement. A vote is expected later this month.
The order for a preliminary investigation came after two Greek news websites reported that lawmakers had received threatening text messages to vote against the deal, the source said.
The probe will seek to determine whether there has been a violation of personal data and inducement to commit a crime, the source added.
The Macedonia accord has strained relations between Greek Prime Minister Alexis Tsipras and his junior coalition partner Panos Kammenos.
Kammenos, defence minister and head of the right-wing Independent Greeks (ANEL) has vowed to reject the deal but at least one of his deputies has said publicly he will support it. It is unclear how other ANEL lawmakers will vote.
The left-right governing coalition has a razor-thin majority with 153 seats in the 300 member parliament. Seven of those seats belong to ANEL.
The main opposition New Democracy party has said it will block the deal. The government hopes the deal will pass with the support of centre-left and independent lawmakers.