According to Calciomercato, the San Siro club are considering selling their skipper for the first time due to his polarising presence in the dressing room.
It's reported that agent Mino Raiola would be keen to help bring Icardi to either United or Madrid. Icardi's wife, Wanda Nara, is his current representative, although it's suggested Raiola—the agent for the likes of Paul Pogba and Zlatan Ibrahimovic—would be ready to work with the Argentina forward.
Italian publication Corriere dello Sport (h/t Calciomercato) said Inter sporting director Piero Ausilio would still like to discuss a new contract with Icardi despite the persistent speculation about his future.
However, the Corriere piece suggested the forward would demand an annual salary of around €8 million (£7 million), an amount the Nerazzurri can't afford. Interest from United and Madrid is again noted, as well as PSG.
Corriere (via Football Italia) also reported that agent Mino Raiola wanted to bring Icardi to Manchester United, but the player would not switch agents from his wife Wanda. Despite that report, Alex Richards of the Daily Mirror reported Raiola "has since sought to position himself as the lead broker in a potential move to the Premier League for the Inter captain."
The striker posted a message on his Instagram account at the end of January that said "to be able to say goodbye is to grow," per BBC Sport, fuelling more speculation about a possible exit.
Additionally, Argentina coach Jorge Sampaoli said he believes Icardi is "tempted" by a move to Madrid, per Veronica Brunati of AS.
The recent murmurs of discontent have hampered Icardi's form on the field. His goalscoring has taken a downturn as Inter have struggled in recent weeks. While he sits on an impressive 18 goals for the 2017-18 season, he's only found the net once in the calendar year.
What Icardi has shown throughout his time at Inter is that if he gets the service, he can be lethal, as these numbers from OptaPaolo illustrate:
There are sometimes spells in matches where Icardi can linger on the periphery, as his work with his back to goal and linkup play aren't outstanding facets of his game.
Where he does excel is in the penalty area. The striker's movement is sharp, while his ability to finish with his left foot, right foot and head make him such a difficult attacker to contain. When Inter were performing well earlier in the campaign, he was frequently the difference-maker.
If Icardi is thinking about moving, it would represent a big change of stance given his past affinity with the club, something manager Luciano Spalletti touched upon earlier in the season to Marca:
Still, if the striker is being divisive in the dressing room and demanding an unattainable salary for Inter, perhaps the summer would be an ideal time for him to make a move.
The player would surely be tempted by the prospect of making a move to Old Trafford, the Parc des Princes or the Santiago Bernabeu. Given his pedigree and the fact Icardi is said to have a release clause of €110 million (£98 million), there will surely be a giant in European football that makes a significant effort to prise him away.