In an address at a conference on the Ohrid Agreement in Skopje, which was released on the European Commission's web site, Rehn said that the implementation of reforms was vital for the country's EU aspirations as well as in the context of challenges faced by the Western Balkans.
"The EU is a community based on shared values. The respect for democracy, rule of law and respect for minorities is the glue that holds the EU together. It is an essential criterion of the accession process. No candidate country can be allowed to start accession negotiations until this criterion is fulfilled," Rehn said.
Macedonia was awarded candidate status in December 2005, but Brussels still refuses to set a date for the start of accession talks, making it conditional on the implementation of reforms.
According to some reports, this could happen in the first half of 2008, when the EU presidency will be taken over by Slovenia.
Rehn warned the Macedonian government that that the pace of reforms over the last year had slowed down and that key reforms had still not been implemented.
Progress is needed in the organisation and functioning of police and judiciary, public administration, and in the fight against corruption and organised crime, Rehn said.
Macedonia should also work on the implementation of the Ohrid Agreement, notably equal representation of different communities in public administration, as well as on the implementation of the Stabilisation and Association Agreement, he added.
Macedonia is in a state of political crisis after ethnic Albanians accused the ruling coalition of violating the Ohrid Agreement by leaving the largest Albanian party out of the government even though it won the largest number of votes of Albanian voters.
The Ohrid Framework Agreement was signed after an outbreak of violence between Macedonians and Albanians in 1991. The agreement granted ethnic Albanians better representation in all government institutions, and the Albanian language became an official language in many parts of the country.
Olli Rehn met in Skopje with Macedonian Prime Minister Nikola Gruevski to discuss reforms in the country and the issue of Kosovo, the France Presse reported.
Rehn said after the meeting that the EU welcomed Macedonia's decision to support UN special envoy Martti Ahtisaari's plan for Kosovo, which paves the way to the independence of the UN-administered province.