Kean is in talks to bring the Hamburg hitman to Ewood Park on a free transfer to boost his attacking options.
Van Nistelrooy, 35 in July, has struggled with injuries recently but has scored nine goals for his club this season.
Then and now: Van Nistelrooy has spent the last year at Hamburg in Germany
'Yes, I can confirm we are interested,' Kean told the ESPN soccernet.
Blackburn face a fight to retain their Premier League status and any move will depend on whether they can avoid relegation.
Van Nistelrooy turned down a move to Rovers before moving to Germanyin January 2010. He also starred for Real Madrid when he left United in2006.
Even if Kean keeps his side up, it will take a lucrative offer to lure the Dutchman back to England.
Kean and Rovers have been short of a regular scorer this season and the return of Roque Santa Cruz on loan from Manchester City has not yet worked out.
Mame Biram Diouf will head back to Manchester United after a loan spell while Benjani looks set to leave the club due to his poor fitness levels.
El Hadji Diouf is another who will depart Ewood Park when he returns from Rangers.
That would leave Jason Roberts as the club's only experienced striker.
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Explore more:People: Roque Santa Cruz, El Hadji Diouf, Jason Roberts Places: United Kingdom, Germany