The Championship outfit have sent scouts to watch the pair, who have helped their current club move into the League One playoffs ahead of the start of 2018.
Leeds are expected to make offers for at least one of the duo next month, but MacAnthony has admitted that he does not want to sell any of the club's key players.
Not likely Ryan me and players agreed in summer to ignore August & Jan transfer rumours unless something mouth watering came up for them & club as promotion our only focus to be fair 👍🏻 https://t.co/c8PNZ9dSpg— Darragh MacAnthony (@DMAC102) 28 December 2017
Forward Marriott has netted 17 goals in 24 appearances in League One this season, and the 23-year-old currently leads the third-tier goalscoring charts.
Maddison has five strikes from 24 outings to his name, and had previously attracted interest from the Championship before penning a new three-year deal in the summer.