The 30-year-old Swede is believed to be under the scrutiny of Siena - who are set to approach Villa and ask about Allback's availability.
Allback is currently down the pecking order at Villa Park, with Juan Pablo Angel and Darius Vassell the preferred starting partnership for David O'Leary.
Villa paid Heerenveen £2 million for Allback in 2002, but he has started just 16 league games since his arrival and has made more substitute appearances.
Allback admitted recently he would consider his future after Euro 2004 and the prospect of a move to Italy could appeal.
Should their move for Allback fail, Siena are believed to be considering a move for Mattia Graffiedi - who spent last season on loan at Fiorentina from Milan.
