Athletic Bilbao president Josu Urrutia has expressed his disappointment about Ander Herrera's move to Manchester United, saying it was totally unexpected as the player had insisted he wanted to stay in La Liga.

The Spanish side tried to block the midfielder's exit by rejecting United's first proposal to meet his €36m (£29m) release clause, but couldn't do anything when the player paid his own buy-out clause directly to the Spanish football federation.

Even though the £29m bid matched Athletic's valuation, they were unwilling to sell the player as due to their Basque-only players rule they will struggle to replace him.

The club president has expressed his surprise about Ander Herrera's decision, as there was no previous indication that he wanted to leave the club.

"For us, Ander Herrera was a player we expected to stay at the club. According to what he said, Ander was delighted to be here and his only aspiration was to stay here," he told AS. "On Monday last week he (Herrera) called me. It was a very short conversation.

"We have had three exceptional cases recently [Fernando Llorente's move to Juventus, Javi Martinez's to Bayern Munich and Herrera's to United]. If it became a trend, it would be dangerous."

Urrutia heavily criticised Herrera last week for his lack of commitment to the club.

"Athletic should aspire to have players whose first choice is to defend the shirt of this club. In this sense, Ander Herrera's decision [to leave the club] doesn't fit with that idea -- so it's a disappointment."

Following the completion of the deal, Herrera defended himself by claiming that he "couldn't turn down" the chance to join such a big club.

"Manchester United, one of the biggest clubs in the world for all its represents, will give me the opportunity to compete for all the trophies and continue to grow as a player and a person in another country and in another League; for this reason I have to tell you 'see you soon' today" Herrera wrote in an open letter to Athletic fans.