Portugal's Treasury Secretary Maria Luis Albuquerque defended a takeover bid by Camargo Correa for Cimpor from suggestions it was against the national interests and the price was too low.
"This operation appears to us the best alternative for the company ... it safeguards the national interests in the most attractive form that was possible to secure," Albuquerque told a parliamentary committee on Thursday after the opposition Socialists demanded the government answer questions on the takeover.
Brazil-based Camargo launched a EUR5.5 (US$7.3) a share takeover bid at the end of last month for the 67.1 per cent of Cimpor it does not own.
Cimpor's board has said Camargo's bid is too low and lacks detail on its plans for the company's future.
Two key Cimpor shareholders, including state-run bank CGD, have already said they are prepared to sell their stakes under Camargo's terms and many analysts expect the bid to succeed.
Earlier this month, Portuguese conglomerate Semapa proposed that some Cimpor shareholders should form a joint holding company to try to keep the company in Portuguese hands.
But Albuquerque said Semapa's proposal "does not meet the objective of CGD deleveraging".