Mar 5 (Reuters) - Portuguese industrial group Bondalti has launched a 329 million euro ($357 million) takeover bid for all the shares of Barcelona-based chemical company Ercros , it said in a statement to the CNMV on Tuesday.

The offer, to be paid entirely in cash, was made at 3.6 euros per Ercros share, representing a 40.6% premium over Monday's closing market price.

Bondalti said its objective was to delist Ercros shares.

The transaction requires the acceptance of more than 75% of the share capital, as well as regulatory and governmental approvals, it added.

The Portuguese company, which also has its Spanish headquarters in Barcelona, has been operating in Spain for more than 20 years and is financially backed by the José de Mello Group.

(1 dollar = 0.9219 euros)

(Reporting by Matteo Allievi; editing by David Latona and Louise Heavens; Spanish editing by Javi West Larrañaga)