Arthur Andersen is understood to be close to announcing a link-up with leading Portuguese firm AM Pereira Saragga Leal Oliveira Martins Judice e Associados.
The move could mark the next stage of the firm's ambition to become one of the largest providers of legal services in Europe by 2000.
Meanwhile, sources close to Andersens in London say that the firm is weeks away from a deal with Simmons & Simmons, despite vigorous denials from both of the practices.
Speculation about an imminent Simmons & Simmons-Andersens link-up has been fuelled by the fact that the long-standing relationship between Simmons & simmons and Spanish practice J&A Garrigues has continued despite the Spanish firm's link-up with Andersens in February this year.
The two firms have been locked in talks since the link-up, with both practices insisting that no decision has yet been made on the future of the relationship.
J&A Garrigues and Simmons & Simmons are continuing to share premises in New York, although the two have separated in Brussels.
However, Andersens' expected link-up with AM Pereira Saragga would add further complications to the relationships.
Andersens is already linked to Portuguese legal network, Groupo Legal Portugues, via J&A Garrigues Andersen. Simmons & Simmons is also a member of this group.
One Simmons & Simmons insider said: “As things stand, Garrigues would be in danger of breaking its agreement with Groupo Legal Portugues if this merger went ahead.
Simmons & Simmons senior partner Bill Knight has consistently refused to comment on whether the firm is in talks with Andersens.