Macedonia's political leaders yesterday reached "conditional agreement" in peace talks on the key issue of the status of the Albanian language, Western mediators said.
EU envoy Mr Francois Leotard said the deal was "dependent on a political accord, notably on the question of the police".
US envoy Mr James Pardew said there was still a lot of "tough" work to do to get an overall peace accord when talks resumed tomorrow.
"That means that nothing is completed until everything is completed. But language we can now set aside and go on to [the issue of] police and the remainder of the framework agreement," he said.
Turning the framework agreement into a final accord is seen as Macedonia's last chance to end a six-month ethnic Albanian rebellion that has threatened to turn into civil war in the Balkan country.
The negotiations, involving the two main Macedonian parties and the two main ethnic Albanian parties, are to take a pause today because of Macedonia's National Day public holiday.
Mr Pardew said yesterday's breakthrough was "a significant development in the negotiating process".
"Language has always been the toughest issue and now we have both parties agreeing to language," he said.
The conditional accord provides for Albanian to be an official language alongside Macedonian in areas where ethnic Albanians make up at least 20 per cent of the population. Albanian could also be used in communications between ethnic Albanian citizens and government departments and agencies, as well as in parliamentary plenary sessions and committees.
The political accord between the leaders of the Macedonian and ethnic Albanian parties came after five days of mediation.
The agreement is a prerequisite for NATO to come into Macedonia to supervise the disarming of ethnic Albanian rebels who have been fighting government forces in the north since February.
Ethnic Albanians make up about a third of Macedonia's two million people. Most live in the north, near the border with Kosovo, and in the west, near Albania.