Some sections of the media recently linked the long delay in confirming a new BMW contract for Nick Heidfeld next year with reports that unhappy reigning world champion Alonso was looking to leave McLaren.
But Theissen, an unabashed admirer of the 26-year-old Spaniard, told the news agency Sport-Informations-Dienst: "They were two completely separate issues."
He was also quoted as saying by Deutsche Presse Agentur: "Alonso is of course a great driver, but this was never a consideration for us."
Theissen, however, insisted that he is "happy" that top drivers like Alonso are now beginning to see BMW as an attractive team to drive for.
Asked specifically if either BMW or Alonso's management had spoken to one another about a collaboration, he answered: "Not seriously, no."
But he said the Spaniard has "very probably observed the development of our team" during 2007.
Theissen also would not confirm reports that Heidfeld's new deal is actually for two more years, plus an option for 2010.
He said: "We have announced the driver pairing only for next year, regardless of the content of the contracts. That will always be the case." (GMM)