The I'm Outta Love singer rescheduled two concerts in Switzerland last week (ends10Apr16) after doctors ordered her to go on vocal rest for four days to tackle the infection.

However, she has now been advised to take more time off to recover and has postponed Thursday and Friday's (14-15Apr16) shows in Essen and Mannheim, in Germany, respectively.

"Anastacia is recovering well but has been ordered by the doctor to take a few extra days vocal rest before she restarts the tour," the announcement on Facebook reads. This will therefore affect the following shows: 14th April 2016 - Essen... Colosseum Theater, 15th April 2016 - Mannheim, Rosengarten... We appreciate your patience and look forward to seeing you on the Ultimate Collection Tour soon - The A Team (heart emoji)."

According to the statement, the tour will resume in Kempten, Germany on Sunday (17Apr16).

The singer, 47, recently thanked her fans for their support during her illness. She tweeted, "Family thanks for keeping me laughing through this upper respiratory infection. Riddles, jokes and your kind positive well wishes are always the best medicine."

In the original statement concerning her Switzerland shows, her representative wrote "Anastacia is devastated with the idea of letting her fans down."

She has rescheduled the Switzerland concerts for June (16) and is working to reorganise her Germany gigs.