Pavarotti has said he wants to retire at 70

Four performances in Canada and one in the US have been delayed until October.

In April the 70-year-old tenor scrapped eight concerts after injuring his back, undergoing treatment in New York.

But Pavarotti's manager said the star developed an infection which forced him to cancel the later dates. He is due to resume his tour in the UK in July.

Intensive therapy

Terri Robson, Pavarotti's manager, said: "Luciano apologises to his many disappointed fans for having to reschedule these concerts.

"Happily, he is now well on his way to recovery and very much looks forward to continue celebrating his career with the Pavarotti Worldwide Farewell Tour."

The postponed concerts are in the Canadian cities of Calgary, Vancouver, Montreal and Toronto, and in Washington in the US.

Tickets from the postponed dates will be valid for the October shows.

Pavarotti is to stay in New York to continue with intensive physical therapy.

His farewell tour has so far lasted more than a year, with no definite final date yet given.