United are preparing a bid for Martinez, with Erik ten Hag keen to bring the Argentine to Old Trafford to bolster their defence.
Arsenal are also keen on Martinez and have hinted they would be ready to bid €30m (£25.8m) this summer.
Reports this week have also claimed United are finalizing a £40m deal for Brazilian winger Antony, who has thrived under Ten Hag since joining Ajax from Sao Paulo in 2020.
However, the Daily Mirror report that Ajax are refusing to sell both Anthony and Martinez, meaning Ten Hag may have to decide which player he would prefer at United.
Ten Hag also wanted Jurrien Timber but the 21-year-old has opted to stay at Ajax to increase his chances of making the Netherlands World Cup squad at the end of the year.
Ajax have already lost Ryan Gravenberch to Bayern Munich this summer, while their leading striker Sebastian Haller has joined Borussia Dortmund for £30million.
Elsewhere, United remain in talks with Barcelona over a deal for Frenkie de Jong.
Reports in Spain on Tuesday night claimed United are £12m shy of Barcelona’s £72m valuation of the Dutch midfielder.
Barcelona are still willing to sell De Jong this summer and plan to use the funds to sign Bernardo Silva from Manchester City.
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https://metro.co.uk/2022/06/22/ajax-respond-to-man-utd-after-antony-and-lisandro-martinez-approaches-16869431/ Ajax react to Man Utd after Antony and Lisandro Martinez approach | Soccer