The women's event is currently being staged in Galle until October 1 with the semi-finals and the finals to be played before the men's semi-finals and final at R Premadasa Stadium in Colombo on October 4, 5 and 7 respectively.
The confirmation was conveyed to Sri Lanka Cricket on behalf of the committee.
Mendis will replace de Silva who is unwell and is unable to compete in the remainder of the event.
Any injury or illness-based replacement requires a written submission to the event technical committee along with a diagnosis from a medical practitioner as to the extent of the injury or illness. Once replaced, a player may not return to the squad save as an approved subsequent replacement for another injured or ill player.
Twenty-six-year-old Mendis is a right-handed batter and right-arm medium pace bowler and replaces de Silva who has the same batting and bowling style.
As with all players in the tournament, the eligibility of a replacement player is subject to approval by the ICC before that player can be officially added to the squad.
The Event Technical Committee of the ICC World Twenty20 Sri Lanka 2012 consists of Geoff Allardice (ICC, chairman), Ajit Jayasekera (host representative), Campbell Jamieson (IDI representative), Ashley D'Silva (host representative), David Lloyd (independent nomination) and Ramiz Raja (independent nomination).
