David Moyes declared on Wednesday that he was "proud" to have managed Manchester United, but said that he understood the "frustration" that had led to his dismissal.

Moyes, 50, was sacked by United on Tuesday after a dismal 10-month tenure in which the reigning champions slumped to seventh place in the Premier League, denying them a place in next season's Champions League.

"During this period of transition, performances and results have not been what Manchester United and its fans are used to or expect, and I both understand and share their frustration," Moyes said in a statement released by the League Managers' Association (LMA).

"I have always believed that a manager never stops learning during his career, and I know I will take invaluable experience from my time as United's manager.

"I remain proud to have led the team to the quarter-finals of this year's Champions League and I remain grateful to Sir Alex Ferguson (his predecessor) for believing in my ability and giving me the chance to manage Manchester United."

The LMA, the trade union for managers working professionally in England, criticised United for the "unprofessional manner" in which Moyes was dismissed.

Chief executive Richard Bevan said the organisation was "very disappointed" that "extensive reports in the press" had announced Moyes's sacking before he "had been spoken to officially by the club".

Although reports about Moyes's departure first emerged in the British media on Monday afternoon, he did not learn of his fate until early on Tuesday morning.

Responding to Bevan's comments, United said that they had not acted irresponsibly.

"We do not accept that it was handled in an unprofessional manner," said a spokesperson.

"The decision was not taken until late Monday night and was communicated face-to-face first thing on Tuesday morning.

"When reports started emerging on internet news sites on Monday afternoon, no decision had been taken at that time."

Moyes added: "Taking charge after such a long period of continuous stability and success at the club was inevitably going to be a significant challenge, but it was one which I relished and never had a second thought about taking on.

"The scale of the manager's job at United is immense, but I have never stepped away from hard work and the same applies to my coaching staff. I thank them for their dedication and loyalty throughout the last season."

British newspaper reports on Wednesday claimed that Real Madrid coach Carlo Ancelotti has been identified as a potential candidate for the United job.

Several papers said that Ancelotti was being considered for the vacancy, along with Netherlands coach Louis van Gaal, who emerged as the early favourite for the post.

However, whereas Ancelotti, the former Chelsea manager, is less than a year into a three-year contract at Madrid, Van Gaal is scheduled to step down from his position with Holland after this year's World Cup in Brazil.

Van Gaal, 62, is currently on holiday in Portugal. Dutch tabloid Algemeen Dagblad reported that he was "maintaining radio silence".

Long-serving midfielder Ryan Giggs has been placed in interim charge of first-team affairs "until a permanent appointment can be made", United said.

The 40-year-old Welshman, who became a member of Moyes's coaching staff at the beginning of the season, is expected to address the media for the first time since taking up his new role on Friday.

Giggs will be assisted by Phil Neville and Chris Woods, both of whom kept their jobs on United's back-room staff despite having been brought in by Moyes, as well as youth-team coach and former team-mate Nicky Butt.

However, Steve Round and Jimmy Lumsden, who were also appointed by Moyes, have both been fired.

Another of Giggs's former team-mates, Paul Scholes, has also been drafted in to provide support.

"It's great to see Paul Scholes here at the Aon Training Complex today, assisting Ryan Giggs, Nicky Butt and Phil Neville," United said in a message on the club's Twitter feed on Wednesday.

News of Moyes's departure met with a favourable reaction on the New York Stock Exchange, where United's shares rose six percent to their highest level since Ferguson's retirement last May.