Cristiano Ronaldo is “outraged” at what he feels is unfair treatment by Spanish tax authorities and is determined to quit Real Madrid and the country.

It is understood the 32-year-old feels he is being singled out for disproportionate treatment after prosecutors accused him of defrauding the authorities of €14.7m (£12.8m).

A source claims the “outraged” Portugal international “feels great indignation” at all the speculation about his tax affairs and a sense of “injustice” at the allegations – which he contests – and has made a decision to leave Spain.

This week Ronaldo’s agency, Gestifute, released a statement which said: “There is no tax evasion scheme ... There has never been any hiding nor any intention to hide anything.”

On Thursday Ronaldo, who signed a new five-year contract in November, posted a picture with his fingers to his lips on Instagram with the caption: “Sometimes the best answer it’s to be quiet.”

The potential availability of the Portugal international, one of the world’s most marketable players, would alert a number of top clubs, plus big-spending Chinese Super League sides looking to make a statement.

However, his Real contract is understood to have a €1bn (£874m) buy-out clause and, in May, Forbes calculated his pre-tax salary as being close to 45m a year.

Ronaldo has helped Real win the Champions League three times, scoring twice in last month’s final as they became the first club to retain the title. He is the competition’s record goalscorer with 105.

He has also won two La Liga titles with the club he joined from Manchester United for £80m in 2009.

Lionel Messi took a similar stance in threatening to quit Spain in 2014, also claiming he had been singled out for special treatment, when he was accused of concealing €4.1m from the authorities.

The Argentinian was found guilty and subsequently lost an appeal against a 21-month prison sentence – under Spanish law sentences under two years are usually suspended – and a €2.1m fine.