Declan Rice’s ambition to play “at the very highest level” was behind his “tough” decision to leave West Ham.

The 24-year-old’s departure from the club he joined a decade ago in a club-record £105million deal – making him the most expensive English player in history – was confirmed by the Hammers ahead of his imminent move to Arsenal.

Rice’s last act as a West Ham player was to become only the third captain in their history, behind Bobby Moore and Billy Bonds, to lift a major trophy after last month’s Europa Conference League victory over Fiorentina.

But the England international wants to play in the Champions League and that is something Arsenal can offer.

In a letter to fans, Rice said his goodbyes after “an absolute whirlwind of emotion” over the last few weeks.

“I want you to know how tough a decision it has been for me to leave an environment that I have loved and cherished so much,” he said.

“This club and its supporters will always be in my heart, and forever a part of who I am.

“Ultimately, though, it has only ever been about my ambition to play at the very highest level of the game.

“Playing on the opposite team to West Ham for the first time will be an unusual experience.

“I’m not sure yet exactly how I will feel, but I also know you will all understand and respect that my professional loyalties have to now lie with my new club.”

Joint-chairman David Sullivan revealed last month the club had a gentleman’s agreement with Rice to allow him to leave this summer after the player turned down the offer of a highly-lucrative new contract.

“I am sorry to see Declan leave us but I believe that everyone at West Ham United should be very proud of the part we have played in his journey from the Academy of Football at Chadwell Heath to becoming the most valuable young player in English football,” he said in a statement.

“I would like to make it clear to our supporters that we did not want to sell Declan. We wanted to build our team around him and made a series of improved, long-term contract offers to secure his future.

“However, once Declan made it clear that he wished to move on and seek a new challenge, the club felt it would not be right to stand in his way, acting in the best interests of West Ham United.”

Rice made 245 appearances for the club, his last helping secure a first trophy since 1980, and manager David Moyes was understandably sad to see him leave.

“I’d like to personally thank Declan for everything he has done during his time at West Ham United,” he said.

“Obviously it is sad when we say goodbye to someone who has been with us for so long but we must now look forward.

“As history shows, no player is ever bigger than the club.

“Our entire focus now is on building upon the success we enjoyed last season, adding to our talented Europa Conference League title-winning squad as we enter our third consecutive season in Europe, and continuing to develop the best young talent through our successful academy.”

Arsenal confirmed Rice’s transfer later on Saturday.

Speaking after West Ham’s 6-2 win over Perth Glory on their pre-season tour, Moyes said on Sky Sports News: “Declan’s gone now, he’s a super player. A really good boy who performed excellently for us here at West Ham.”