It's suggested in the report that discussions about a new deal had initially taken place in December, but the 22-year-old's agent has not received anything since from United. The former Monaco man is reportedly "astonished" at United's ponderous approach to the new contract.
Spurs are said to have taken an interest in Martial, while Inter Milan are also noted as admirers of the United No. 11.
Sport Witness suggested on Twitter that these reports should probably be taken seriously given the source of them:
Martial's contract is set to expire at Old Trafford in 2019, although United do have the option to extend that by a year.
The youngster made a surprise move to the Red Devils in 2015. After a tremendous debut campaign, he's since gone on to establish himself as a fan favourite. Martial has netted some big goals for United and can light up any match with his dazzling feet.
He's not a surefire starter under manager Jose Mourinho at the moment, though. Martial has made 25 Premier League appearances this term, although only 15 have been starts, including just four appearances in the starting XI in the UEFA Champions League.
As noted by Miguel Delaney of The Independent, Martial has been a little hindered by the cautious approach of the United boss:
At 22, it's no surprise that there are still rough edges in Martial's game. But when he is on form, he's one of the best wide forwards around.
The France international can be devastating with his powerful running, blistering pace and remarkable agility. Additionally, when he does find himself in goalscoring situations, Martial has showcased tremendous composure and rarely squanders clear opportunities.
Harnessing those qualities has proven to be a challenge at times, especially since the arrival of Alexis Sanchez in January. While a front three of Sanchez, Martial and Romelu Lukaku has the potential to be effective, the youngster has been shunted out to the right flank at times.
Per BT Sport's Ian Darke, it appears as if Martial will need to do some adapting to his new role:
Given his age, his temperament and his natural talent, that's something the youngster should be able to do eventually. It makes the reports that United are being sluggish to extend his stay at the club all the more peculiar, as so many sides would love to have such a tremendous attacker in their setup.
Spurs are one of those and Martial would tick a lot of boxes for the manner in which Mauricio Pochettino wants his side to play. Even so, it's tough to envisage a scenario where United sell such a bright prospect any time soon, especially to a serious title rival.