Jack Wilshere says he is disappointed but insists he "can still contribute at the very top of the game" following his release by West Ham.
The midfielder leaves the Hammers after making 19 appearances in just over two years and with nine months left of the deal he signed with the club in 2018.
"I'm still only 28 and feel fit, strong and ready to play," tweeted Wilshere.
"I am still incredibly hungry, ambitious and desperate to play football and achieve success."
Wilshere joined the Hammers, the club he supported as a boy, on a three-year deal in July 2018 after leaving Arsenal.
But he has made only 16 league appearances since and featured once for the Hammers this season, in the 5-1 victory over League One Hull in the Carabao Cup.
However, he insists that his absence from the team has not been fully down to the injury problems that badly affected his time at the Gunners, especially of late.
"Despite all my best efforts and intentions, it has not worked out as I expected," he wrote.
"I have been fully fit for a large period of time at the club, including over the course of the last eight months - training hard every day - but unfortunately have not been given the opportunity to play.
"Although of course I am frustrated that I was not fully able to showcase what I am capable of at West Ham I remain convinced I can still contribute at the very top of the game.
"I'm now looking forward to the future and hope to be able to make an announcement about the next stage of my career in due course."
An extremely talented player, Wilshere made 197 first-team appearances for Arsenal and was part of the 2014 and 2015 FA Cup-winning sides.
He has 34 England caps, the last of which came in the 2-1 defeat by Iceland in the 2016 European Championship last 16.
'Managers don't trust Wilshere any more'
Former England defender Micah Richards on BBC Radio 5 Live
For Jack Wilshere now, managers just don't trust him any more, and it's sad because I don't like to see that of any player.
He's still only 28 and we all know he's got great ability but he just hasn't managed to do it often enough and unfortunately for him, injury has played a massive part in it.
I feel his pain. When you've been hampered by so many injuries and you're trying to get back and trying to prove to people you can do it and you're almost trying too hard, I feel for him.
He's still got time. We know he's not going to be a top-four - maybe not even a top-eight - player any more. There will be someone out there that will trust him.
Tomori snubs Hammers as Cullen departs
West Ham midfielder Josh Cullen, who spent the past two seasons on loan at Charlton, has joined Anderlecht on a permanent basis and striker Xande Silva has been loaned to Aris Thessaloniki.
Cullen, a 24-year-old Republic of Ireland international, came through the Hammers academy and made 10 appearances.
Silva, 23, has made two senior appearances since joining from Vitoria Guimaraes in 2018.
Chelsea defender Fikayo Tomori has snubbed the offer of a deadline-day loan move to West Ham.
West Ham agreed a deal with Chelsea to take Tomori for the remainder of the season but the 22-year-old England international opted against the move.
It was disappointing for West Ham, who also failed to land another Chelsea player, Antonio Rudiger, and Burnley's James Tarkowski in their bid to add another central defender to manager David Moyes' squad.
In addition, West Ham winger Felipe Anderson could be loaned to Porto.
The Portuguese transfer window closes on 25 October, but Porto would need to register the 27-year-old Brazilian by Tuesday if they want him to play in the Champions League this season.