The San Francisco 49ers have signed Arik Armstead to a five-year contract extension, while DeForest Buckner is reportedly heading elsewhere in a trade.

Selected by the franchise in the first round of the 2015 draft, Armstead has appeared in 62 games - 43 of them as a starter - in his NFL career with San Francisco.

The defensive lineman enjoyed an outstanding 2019 season too, registering 54 tackles, 10 sacks and two forced fumbles as the 49ers reached the Super Bowl, albeit they lost to the Kansas City Chiefs in Miami.

His new deal runs through the 2024 season and while details were not officially disclosed, it is reportedly worth $85million.

"We are very pleased to have come together with Arik and his representatives to complete this contract extension prior to free agency," said 49ers general manager John Lynch.

"Arik's physical tools and versatility have allowed him to be highly productive in our style of defense, and we look forward to watching him take his game to an even higher level as he grows within our scheme.

"Arik has been an impact player on the field and a difference-maker in our community, and we are excited for what the future holds for him."

Buckner, however, is said to be on the move from San Francisco, with NFL insiders on social media reporting the defensive lineman is to be traded to the Indianapolis Colts.

The 49ers get the 13th pick in this year's draft in return for a player who made the Pro Bowl in 2018, while Buckner will net a lucrative contract extension from his new employers.