Dreamgirls' Amber Riley battling pneumonia

Amber Riley has been forced to pull out of several performances of West End musical Dreamgirls due to illness.

The former Glee star was cast as Effie White in the stage production but mere weeks after the show's opening night on 14 December (16) she became sick and has reportedly been on vocal rest since before the Christmas holidays.

Producers of the show issued a statement on Twitter on Wednesday (04Jan17) in which they revealed the actress has nearly recovered from a battle with pneumonia and is set to return to the stage shortly.

"As previously stated, several of the cast members of Dreamgirls have been ill over the holiday season, including Amber Riley who was diagnosed with pneumonia," the statement reads. "The company has been working with doctors to ensure that they all recover as quickly as possible, taking every precaution that they do not come back too quickly and become ill again.

"Fortunately, Amber is now in the final stages of recovery and is expected to return to the show in the next few days."

The producers drafted in Broadway star Marisha Wallace, who played Effie in a Dallas, Texas production, to play the role alongside Amber's other alternate Karen Mav in the star's absence, and it seems she will continue to be used for certain performances.

Amber retweeted the statement and wrote to fans: "Thanks for the support and well wishes. I'm looking forward to completely healing and getting back to @DreamgirlsLDN as soon as possible."

A number of performances of Dreamgirls had to be cancelled after multiple members of the cast were struck down with a mystery illness days before the official opening at London's Savoy Theatre.

Amber, 30, has been nominated for a WhatsOnStage Award for her performance but she faces competition from Sheridan Smith (Funny Girl), Glenn Close (Sunset Boulevard), Carrie Hope Fletcher (Chitty Chitty Bang Bang), and Devon-Elise Johnson (Half a Sixpence).