Former Watford forward Ighalo is with Chinese club Shanghai Shenhua and has two years left on his contract while Slimani is on loan at Monaco from Leicester.
Nigeria international Ighalo scored 17 goals in 55 Premier League appearances for the Hornets before securing a move to Chinese League One in 2017.
Slimani has 13 goals in 46 appearances for his parent club Leicester but has been loaned out to Newcastle, Fenerbahce and Monaco since his arrival at the King Power Stadium in 2016 from Sporting Lisbon.
After their 2-0 defeat to Burnley at Old Trafford in midweek, Ole Gunnar Solskjaer indicated that the club – six points behind fourth-placed Chelsea after successive defeats – are in need of ‘quality’ signings, with Paul Pogba as well as Rashford currently sidelined.
A £30m offer has been submitted for Birmingham City’s 16-year-old Jude Bellingham.
Sporting Lisbon’s Bruno Fernandes remains intent on a move to Old Trafford, but talks between the clubs have stalled, with United currently £10m short of Sporting’s valuation.
Speaking ahead of an FA Cup tie at Tranmere, Solskjaer insisted the club was still working on reinforcements in a “difficult” market.
“It’s not going to be a quick fix. And it’s not going to be like eight players in or 10 players in one transfer window,” he said.
“We’ve had one proper transfer window in the summer because the Januarys are difficult, but we are trying to do something now.”
Marcus Rashford’s injury has certainly left Manchester United even lighter up front following Romelu Lukaku’s departure in the summer.
The club were confident of signingErling Haaland from Red Bull Salzburg this month, but he chose Borussia Dortmund instead, going on to score a 20-minute hat-trick on his debut for the German side.
United have considered various short-term solutions, including Edinson Cavani, Dries Mertens and Mario Mandzukic, but they are all 32 or over and United might be better off pursuing Lyon’s Moussa Dembele.
“United do need experience and they know that, but the trouble with players like Cavani is that they are maybe too experienced, in terms of their age,” says Sky Sports News’ James Cooper.
Dembele, who turns 24 in July, has experience of playing in England and Scotland with Fulham and Celtic respectively. He has fired 36 goals in 76 appearances for Lyon since moving to the club in 2018, and figures highly on Manchester United’s long-term wishlist.
“I think there is a realisation that they can’t get someone in for the short-term because there aren’t many suitable options out there,” says Cooper.
“But what they might try to do, rather than look for that short-term fix, is to try and bring one of their world-class targets for the summer forward to January and that’s why we have seen them sending scouts to watch Dembele.
“What the Burnley game proved is that without Rashford, you haven’t got the players there who can take the two or three big chances that come up per game. Mason Greenwood is too young to play in every game, and Anthony Martial is not scoring enough to lead the attack.
“They need someone more ruthless who can slot in, but the difficulty is that every club in the world now knows they are desperate.
“Ole has been very noble about making sacrifices and getting rid of (Romelu) Lukaku in the summer, but in hindsight he knows he should have got another body in there. Dembele could now be that man but it won’t be easy to get him.”