MADRID (Reuters) - Axel Weber, the chairman of UBS, warned his Santander counterpart Ana Botin in September 2018 the Swiss bank would apply compensation rules to Andrea Orcel in case he quit, the Swiss banker told a Spanish court on Wednesday.

The Swiss bank strips any employee leaving voluntarily to join another financial company of any deferral payments, Weber said.

Andrea Orcel, who was UBS's top investment banker at the time, is suing Santander in a Spanish court over the withdrawal of an offer to make him CEO on disagreements over a financial compensation of deferral payments owed by UBS.

(Reporting by Jesús Aguado and Emma Pinedo; Editing by Inti Landauro)