Leicester’s attempt to reinforce their squad before the end of the January transfer window have been dealt a blow after Milan rejected a proposed offer of €16m (£12.1m) M’Baye Niang and insisted he is not for sale.

With his side three points clear at the top of the Premier League, Claudio Ranieri is keen to add his to attacking options but has so far been frustrated after seeing Sampdoria striker Éder join Milan’s neighbours Internazionale on an initial loan deal instead.

That led Leicester to sound out Milan over Niang, the 21-year-old forward who has scored two goals in 10 Serie A appearances so far this season. However, Milan are unwilling to sell a player who is contracted to the club until 2019 and have told Leicester they would not allow him to leave, with chief executive Adriano Galliani later revealing an official offer was never lodged.

“Milan don’t want to sell M’Baye because they have a lot of confidence in him,” Niang’s agent Moussa N’Diaye told Guardian sport.

“He is doing well and everything is good for him in Italy so they have rejected the interest. It’s good for him that English clubs are taking an interest in his career but at the moment he is happy to stay.”

Niang, who started his career at the French side Caen, turned down interest from Tottenham and Arsenal before moving to Italy in August 2012. He has since been loaned out to both Genoa and Montpellier but returned to San Siro last summer.

However, Leicester still retain hope of adding to their squad and have had a bid of around £15m rejected for CSKA Moscow’s Ahmed Musa. Manchester United have also been linked with the Nigeria forward, who is understood to be valued at around £19m by the Russian club, although his agent remains doubtful whether a deal will be struck.

“There is little time left in the transfer window,” Tony Harris told the Russian media outlet Sport Express. “We are waiting for developments. Sometimes the situation is changing in the last few hours. But Ahmed will most likely remain in Moscow.

“Playing in England is tempting for each player, and Musa is no exception. He would willingly go there. But it is necessary for his club to agree to the proposed terms.

“However, there is no urgency. Ahmed is happy in Moscow. But if there is a suitable offer, he would certainly consider it.

“I can only say that the interest is from a number of clubs, not just Leicester. Once a proposal is acceptable to all parties, we will consider it.”

Meanwhile Éder, who has signed a two-year loan deal with Inter, admitted he preferred to remain in Italy.

“Leicester were interested too, but I spoke to Mancini and in all honesty didn’t think much when I found out Inter were interested,” he said. “I know the importance of the club and shirt, so it was an easy decision, especially as it allowed me to stay in Italy.”