"The opposition got the most votes and support of the citizens," said
Mr Buckovski, the leader of the Social Democratic Union. The SDSM is the main party in his multi-ethnic governing coalition.
The statement came about an hour after the centre-right VMRO-DRMNE party of opposition leader Nikola Gruevski claimed victory in the election.
Mr Gruevski's party says that according to their estimates, VMRO-DPMNE won 55 of the parliament's 120 seats, enough to oust the governing coalition of Prime Minister Vlado Buckovski.
"Nikola Gruevski is the next prime minister of Macedonia," said a spokesman of the VMRO-DPMNE party at a post-election rally in the capital Skopje.
"I congratulated its (VMRO-DPMNE) leader Nikola Gruevski on the victory in a telephone call," said Mr Buckovski.
"But Macedonia is the main winner as the citizens showed that they could vote in free and fair elections," he added in a reference to the close international community scrutiny of the vote.
"We want to tell the citizens that we'll be in the parliament to continue to work for Macedonia to be part of the EU integration," Mr Buckovski said.
However, the State Electoral Commission has so far only announced preliminary results of a portion of the votes counted pointing to victory of Mr Gruevski's party. It is expected to reveal more results overnight.
The parliamentary election was closely watched by Brussels, which accepted Macedonia as an EU candidate in December last year.
Macedonia hopes to join NATO and the 25-nation European bloc in 2008 and 2012 respectively.
But European leaders first wanted to see free and fair elections in the country.