Slaughter and May’s Spanish ally Uria & Menendez has secured a merger with top five Portuguese firm Vasconcelos F Sa Carneiro Fontes & Associados in an audacious deal that forges the first pan-Iberian heavyweight.

Uria will merge with the 50-lawyer Vasconcelos, a long-term referral ally of Allen & Overy (A&O), next month – giving the 300-lawyer Spanish firm the third-largest legal practice in Portugal and a key position in the emerging Iberian market.