Denmark's Queen Margrethe II was discharged from hospital on Thursday after back surgery last week though a full recovery is expected to last months, the Danish Royal House announced.

The 82-year-old, Europe's longest reigning monarch, underwent a "major" back operation last Wednesday at Rigshospitalet, the country's largest hospital.

"The medical team responsible for the operation and the subsequent hospitalisation is satisfied with the process and with The Queen's condition," the court said in a statement.

The Danish monarch is now staying at her palace in Amalienborg and will undergo "a lengthy physical rehabilitation process, which may extend over the next few months", the court warned.

Crown Prince Frederik will "continue as regent for the time being."

The palace had already announced that a number of events in its official programme would be postponed, cancelled or attended by other members of the royal family as a result of her operation.

The exact nature of the operation has not been specified. The queen had undergone a lumbar canal operation 20 years ago.

The queen, who was widowed in 2018, is extremely popular in Denmark. More than 80 percent of Danes say they support the monarchy, with thousands turning out to celebrate her 50th anniversary on the throne last year.