(Bloomberg) -- A Lisbon court has ordered the “preventive seizure” of a 26% stake in Portuguese telecommunications company NOS SGPS SA that’s controlled by Isabel dos Santos, Africa’s richest woman and the daughter of Angola’s former president.

ZOPT SGPS SA, a venture that holds 52% of Lisbon-based NOS, received a notice from the court on the seizure of half of that stake, according to a regulatory filing on Saturday. Dos Santos and Sonaecom SGPS SA, a unit of Portuguese holding company Sonae SGPS SA, each control half of ZOPT.

Portugal’s public prosecutor in February issued a freeze order on the bank accounts of dos Santos, following a request from Angolan authorities for international cooperation. In December, an Angolan court froze the local assets of dos Santos, as well as those of her husband and one of her executives, after prosecutors alleged they engaged in deals with state-owned companies that led to the government incurring losses of $1.14 billion.

Dos Santos has denied any wrongdoing. Her other investments in Portugal include indirect stakes in oil company Galp Energia SGPS SA and engineering firm Efacec Power Solutions. In February, Abanca Corp Bancaria SA of Spain agreed to buy 95% of Lisbon-based lender EuroBic, in which dos Santos controls a 42.5% stake.

The seized NOS shares won’t have rights to vote and to receive dividends, according to the filing released by Sonaecom. Sonaecom said the court’s decision “seriously harms” its own interests, even if it’s a firm that’s “completely unrelated” to the ongoing judicial process.

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