McDermott leaves Royals
Reading are 19th in the Premier League, level on points with bottom club Queens Park Rangers, after their 2-1 defeat at home to relegation rivals Aston Villa on Saturday.
That was a fourth loss in succession for the Royals, leaving them four points adrift of 17th-placed Villa, and the club's owner Anton Zingarevich decided a change was needed.
A statement on the club's official website read: "Reading Football Club has announced today the departure of manager Brian McDermott.
"Owner Anton Zingarevich wishes to place on record his thanks to Brian, who had achieved great success with the club since taking over as manager in December 2009.
"Brian gained promotion to the Barclays Premier League last year for only the second time in the club's history thanks to a remarkable run at the end of last season.
"However, in our current situation, Anton Zingarevich felt a change was necessary."
The statement said the Berkshire club would start their search for a successor to McDermott immediately, adding: "It is hoped that a new manager will be in place as soon as possible to lead the fight against potential relegation."
McDermott, whose only previous experience of management had come with Slough Town and Woking, took charge of Reading in 2009 when Brendan Rodgers left the club.
Reading striker Jason Roberts said McDermott, who guided the club to the Championship title last season, deserved gratitude for his efforts.
He told Sky Sports News: "He's a football man and a good man and I just think at this moment in time we take stock of what he has achieved and place on record our thanks.
"I as an individual player and I'm sure the others would like to place on record their thanks for what he and his (backroom) team have achieved for us."
Paolo Di Canio, the former manager of local rivals Swindon Town, is the early favourite to succeed McDermott. The Italian was at the Madejski Stadium to see the defeat to Villa on Saturday.
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