"Turkey is not a part of Europe and will never be part of Europe," Mr Van Rompuy said during a meeting of the Council of Europe on the subject of Turkey´s possible entry into the EU, held in the Belgian parliament on December, 2004.
During the speech, the Belgian leader underscored Europe´s Christian "fundamental values," which would be undermined by admitting Turkey into the union.
"An expansion of the EU to include Turkey cannot be considered as just another expansion as in the past. The universal values which are in force in Europe, and which are also fundamental values of Christianity, will lose vigour with the entry of a large Islamic country such as Turkey," the then opposition politician said in a speech that until now has remained buried.
Belgian officials confirmed to this website that the speech was made, but noted that the comments were made when in opposition.
Anticipating that the UK, which does not favour Mr Van Rompuy as a candidate for the EU top job and which is pro-Turkey, would immediately jump on the speech as an argument against the Belgian leader, one official said: "Things that are said in opposition, as David Cameron will soon find out, are different from what you find yourself saying when in government."
"Serious politics, however, is to judge someone by what they say and do when in power," the official said.
Nevertheless, it is understood that British diplomats are not particularly concerned.
"If we ruled out all the politicians that had said awkward things in the past, we´d have a very short list indeed," said one.
Mr Van Rompuy is said to have the backing of France and Germany for the presidency post, set to be decided along with the new EU foreign policy post at a meeting of EU leaders on Thursday evening (19 November).
The question of whether Turkey - an official candidate - should be a full member of the European Union has long divided member states.