The San Francisco 49ers have agreed to trade quarterback Alex Smith to the Kansas City Chiefs, league sources confirmed to ESPN.

Kansas City will trade its second-round pick in the 2013 draft -- the second selection (No. 34 overall) in the round -- as well as another conditional mid-round pick in 2014 to acquire Smith from San Francisco, a league source told ESPN.

The 49ers now own 15 picks in the 2013 draft.

As a result of the trade, the Chiefs are expected to release former starting quarterback Matt Cassel, league sources told ESPN. Cassel has two years remaining on a $63 million, six-year deal he signed with Kansas City after he was acquired in a trade from the Patriots in 2009. He failed to live up to the lofty contract, however, and was benched during the 2012 season.

At this point, Smith will play under the terms of his remaining contract, which calls for a guaranteed base salary of $8.5 million in 2013. There have been no discussions between the Chiefs and Smith's representatives about negotiating a new contract.