LISBON, July 17 (Reuters) - Portugal Telecom is considering taking legal action against Banco Espirito Santo, which sold it 847 million euros in commercial paper issued by a holding company of the bank's founding family that has not been repaid, sources said.
Holding company Rioforte failed to pay back the commercial paper when it matured on July 15, forcing a revision of the terms of a planned merger between PT and Brazil's Grupo Oi, with PT's stake in the joint, new company dropping to 25.6 percent from 38 percent.
Portugal Telecom is pondering taking BES to court due to the non-payment as the commercial paper was bought with funds deposited at BES bank accounts, a source close to the process told Reuters on Thursday.
Another source said debt investment into commercial paper like this was seen as being risk-free and Portugal Telecom was never warned by the bank about the possibility of non-payment, having no capacity to know about potential irregularities at the holding companies.
Portugal Telecom declined to comment.
A BES spokesman pointed to the bank's July 10 statement in which it said that institutional clients "are considered qualified investors, in accordance with applicable legal criteria, hence with more capacity to assess risk."
A lawsuit like that could potentially open the door to other companies and large investors suing BES for selling them debts issued by the family's companies which were seen as being safe. (Reporting By Sergio Goncalves, writing by Axel Bugge, editing by Andrei Khalip)