Unipol Assicurazioni, the Italian insurer, is in talks to buy the 28% stake in Banca Nazionale del Lavoro held by shareholders opposed to the €6.4bn ($7.6bn) all-share takeover by Banco Bilbao Vizcaya Argentaria, the Spanish bank.

Such a move would trigger a full takeover offer from the insurance group. Unipol already holds a 10% stake in BNL.