O Jogo says the exciting Uruguay international has attracted a firm approach from Newcastle this month.
However, the 22 year-old has resisted the enquiry, making it clear he wants to see out the season with Benfica before considering all offers in the summer.
Nunez also has concerns about joining Newcastle's relegation, with no guarantees of beating the drop.
Newcastle had one offer of €50m for Nunez rejected in December and were prepared to meet Benfica's €60m valuation this month.
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