Russell Watson worked in a factory before his singing took off

The benign lump was discovered while classical tenor Watson, 39, was recording his new album in Los Angeles.

He flew back to London for a five-hour operation on Monday, which successfully removed the tumour.

Watson's spokeswoman said the tumour was pressing on his optical nerve and would "almost certainly" have ruined his sight had it been left any longer.

The singer was examined in the US last week after developing severe headaches and impaired vision.

He had to wait two days to find out if the tumour was malignant or not, during which he carried on recording before flying back to the UK.

Watson (right) won BBC talent show Just The Two Of Us

The operation took place at St George's Hospital in south London.

The tumour, called a pituitary adenoma, was removed through Watson's nose said Bill Holland, managing director of Watson's record label, Universal Classics and Jazz.

"They had to be very careful the way they did it, because of his vocal cords, we had to ensure that there'd be no damage," he said.

Watson's spokeswoman said he was grateful to hospital staff.

"Russell wishes to pay his sincere thanks and appreciation to the entire medical team at St George's Hospital who successfully carried out the operation," she said.

Album delay

"He is obviously very relieved that the operation has been a success and is in good spirits. He is now resting and we are told by the doctor he will make a complete recovery," she added.

Watson's album, due out in November, will now be released in early 2007. Further recording is on hold until Watson has fully recovered from the operation.

But his UK tour in November and December is still expected to go ahead.

The Salford-born tenor, who used to be a factory worker before he turned to singing, has sold more than 4 million albums worldwide.