Blanc is a big admirer of Silvestre and he is believed to have enquired about the French international last summer.
Silvestre's future at United is uncertain as he has just one-year remaining on his contract and he is well down the pecking order at Old Trafford.
The 30-year-old could be tempted to return to France for regular first-team football and the prospect of Champions League football at Bordeaux next season could sway Silvestre's decision.