Dutch firm Guanabara Holdings has upped the ante in its hostile takeover attempt of Irish carbon credit companyEcoSecurities with an increased and final offer.Guanabara has raised its offer terms from 77p in cash per EcoSecurities share to 90p per share.The Dutch company said the offer terms would not be increased. The offer period has been extended until 1:00pm (Dublin time) on 18 September and will not be extended further unless the offer is unconditional as to acceptances by the deadline.Notwithstanding the above, the company reserves the right to amend the offer terms should a competing bid for EcoSecurities emerge.Guanabara has received acceptances in respect of about 25.53% of EcoSecurities' issued share capital. That puts it halfway towards succeeding in its takeover attempt after the company lowered the threshold for the offer to be declared unconditional to 50% from 80%.