RICHMOND has confirmed assistant coach Mark Williams is battling cancer.

The 56-year-old was diagnosed with lymphoma following tests over the weekend.

He will begin treatment shortly, while continuing his role as senior development coach at the club.

"As we always do at Richmond, we'll support Mark and his family during this time," general manager of football Dan Richardson said in a statement.

Williams spent 12 years as senior coach at Port Adelaide and delivered the club its first AFL premiership in 2004.

Power chief executive Keith Thomas said Williams will be in the thoughts of the entire Port Adelaide community.

"The Williams family name is synonymous with Port Adelaide and 'Choco' is loved and revered by so many of our supporters, past players, volunteers, staff and administrators,"  Thomas said.

"Only a few weeks ago he returned to the club to celebrate the 10th anniversary of our first AFL premiership and as always he stole the show.

"On behalf of the entire Port Adelaide community we wish him well in his treatment."

Williams spent two years at Greater Western Sydney as Kevin Sheedy's assistant before joining Richmond at the completion of the 2012 season.

He also played 200 VFL games for Collingwood and Brisbane, as well as over 150 SANFL games, in a playing career spanning 17 years.