A spokeswoman said Prince Philip, 86, was taken to King Edward VII's Hospital in central London for "assessment and treatment for a chest infection."
"His royal highness's program of engagements for the weekend have been canceled," the spokeswoman said on condition of anonymity in line with palace policy.
The British Broadcasting Corp. reported that he was admitted to hospital Thursday night.
Philip has been married to the queen since 1947. A member of the Greek royal family, he renounced his royal title when he became a naturalized British subject in 1947.
He joined the Royal Navy in 1939, and saw active service throughout World War II, rising to the rank of Lieutenant. After Elizabeth became queen, Philip gave up his naval career to support her.
He has no constitutional role other than as one of the queen's privy counsellors.
Philip is a great-great-grandchild of Queen Victoria.
The Duke of Edinburgh's illness comes as a 10-year investigation into the death of Princess Diana is concluding. The coroner leading an inquest into the death of Princess Diana on Wednesday sent the jury out to consider its verdict on how she and her boyfriend, Dodi Fayed, died in a Paris car crash more than a decade ago.
Lord Justice Scott Baker told the jury to take as long as they need to weigh the evidence from the six-month long inquest into how Diana and Fayed died in the car accident in a Paris tunnel while being trailed by photographers on Aug. 31, 1997.
More than 240 witnesses have given evidence at the inquest, reports CBS News correspondent Sheila MacVicar, and the entire process has cost millions of dollars.
Some of the witnesses were Diana's close friends, Prince Philip's private secretary, a former head of the Secret Intelligence Service and Diana's former butler, Paul Burrell.
"There is no pressure of time," Baker told jurors. "Take as long as is necessary."
Among the last questions he put to the jury was whether Diana and Fayed would have survived had they worn their seat belts and whether Diana would have lived had she been taken to the hospital more quickly.
Baker told the jury that the conspiracy theory promoted by Dodi's father, Mohamed Al Fayed - that the couple were killed in a secret-service plot masterminded by Prince Philip - "has been minutely examined and shown to be without any substance."