The protesters challenged a heavily patrolled police cordon late Friday in the northern city of Thessaloniki where left-wing Prime Minister Alexis Tsipras spoke to supporters in a televised address.
Under the proposed deal, Greece's neighbor will change its name to "North Macedonia" and Athens would drop its objections to the country's accession to NATO and eventually the European Union.
Opponents of the agreement, including the opposition conservatives, argue that it would fail to safeguard Greece's ancient Macedonian heritage and would pose a potential threat to its territory.
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