MILAN (Reuters) - Investors holding more than 50 percent of Abertis' (>> Abertis Infraestructuras) shares have expressed non-binding support for a takeover bid on the Spanish toll road operator launched by Italian rival Atlantia (>> Atlantia), two Italian sources said on Wednesday.

However, one of the sources said that Abertis' top investor Criteria Caixa - the financial arm of a politically connected and powerful banking foundation - has not yet committed to taking up Atlantia's offer, which started last week and will end on Oct. 24.

Atlantia and Criteria Caixa were not immediately available for comment.

German construction group Hochtief (>> Hochtief), controlled by Spain's ACS (>> ACS Actividades de Construccion y Servicios), is expected to present a counterbid for Abertis later on Wednesday, people close to the matter told Reuters.

(Reporting by Paola Arosio, writing by Silvia Aloisi, editing by Francesca Landini)