Macedonia's parliament on Friday delayed the final stage of a debate on whether to launch the procedure to constitutionally change the country's name in line with a breakthrough diplomatic agreement with Greece.

The debate, which has been ongoing since Monday, was due to continue at noon (1000 GMT) and to be followed by either a vote or a time for the vote. 

It was postponed until 3 pm, amid conflicting reports on whether Prime Minister Zoran Zaev had or had not mustered the two-thirds majority required to begin the process of amending the constitution for the name change he promised Greece.

Zaev's coalition is well short of the necessary support and will require several lawmakers from the nationalist opposition - which rejects the name change - to break ranks and support him.

Antonio Milososki, a lawmaker from the nationalist VMRO party, blasted the delays, accusing Zaev's bloc of attempting to blackmail the opposition into voting in favour of the name change; he urged parliamentary Speaker Talat Xhaferi to immediately call the vote.

"We are watching the government drag on with the session," Milososki told reporters in Skopje, adding that the vote would show that Zaev "does not have the majority" to amend the constitution.

It was unclear late Friday afternoon what the next move will be and when.

Zaev promised early elections if parliament refuses to endorse the change.

He and his Greek counterpart Alexis Tsipras agreed in June that Macedonia would change its name to the Republic of Northern Macedonia and that Athens would in return stop blocking its neighbour from joining NATO and opening EU membership talks.

Greece claims the name Macedonia and its historic legacy for its northern province. The diplomatic row erupted after Macedonia emerged from the disintegrating former Yugoslavia in 1991.

Even if Zaev manages to push the name change through despite opposition, it is unclear whether Tsipras will be able to do the same and have it ratified in the Greek parliament.

Greek nationalists, including Tsipras' junior coalition partners,  oppose allowing Macedonia to use that name in any form. 

Athens' chief negotiator with Macedonia, Nikos Kotzias, resigned this week amid a row with Tsipras' junior coalition partners who oppose the agreement.