Cesar Tordesillas

The Buffalo Bills have signed free-agent quarterback Kevin Kolb to a two-year contract, adding another starting option to their list of play-callers.

A league source said the deal, reportedly worth around $13 million, was approved by both sides Saturday night.

The five-year veteran Kolb and Tarvaris Jackson will fight it out for the starting job vacated by Ryan Fitzpatrick, who was released by the Bills recently. Jackson signed a one-year deal last month.

The Bills are expected to pick a quarterback in the NFL Draft and develop him into a starter. However, with the addition of Kolb, the Bills will not be rushed to put a rookie quarterback into action immediately.

Kolb is 9-12 as an NFL starter and has had some good moments on the field, helping the Arizona Cardinals to a 4-0 start last season.

However, injuries has derailed Kolb's career, limiting him to just six games last season. He was sidelined for the year in Arizona's loss to the Bills in October due to detached ribs and a sprained shoulder.

Kolb suffered a serious concussion that caused him to miss the last three games of the 2011 season. He missed two games in the 2010 season due to a concussion, as well.

Kolb was released by the Cardinals earlier this month. He signed a five-year, $65 million contract with the Cardinals in July 2011, $12 million of which was guaranteed.

Overall, Kolb played in just 15 games with the Cardinals over two years, going 255 of 436 for 3,124 yards, 17 touchdowns and 11 interceptions.

Jackson has a 17-17 record as a starter. Jackson was acquired by the Bills last August for a seventh-round draft pick.

However, Jackson spent the entire season as the No. 3 quarterback in coach Chan Gailey's offense. Jackson was re-signed by the Bills to a one-year contract in February.

Bills Sign Free-agent Quarterback Kevin Kolb - NFL 2013