On Sunday (AEST), reigning European champions were eliminated from the tournament in Russia after losing 2-1 in their round of 16 match to Group A winners Uruguay.

"The organisation surprised in a good way," Ronaldo told Brazilian website Globoesporte. 

"I think the tournament is very well-structured, a lot was done in terms of security. I've been happy here. Things didn't go as planned (for Portugal), but at the security level, (the tournament is) very good."

The 33-year-old forward scored four goals at this year's World Cup, including a hat-trick against Spain in the team's first match at the tournament.

The 2018 FIFA World Cup kicked off on June 14 and will continue until July 15, with the matches being played in 11 cities across Russia.