Free agent defensive end Cliff Avril and the Seattle Seahawks reached agreement on a contract Wednesday that addresses one of Seattle's big offseason desires to improve the pass rush along the defensive line.

A person with knowledge of the situation confirmed the agreement to The Associated Press. The person spoke to the AP on condition of anonymity because the agreement is still pending a physical and team had not announced the deal. NFL.com first reported the deal.

Avril immediately helps Seattle's most glaring offseason need in adding depth along the defensive line. Seattle is unsure of the status of defensive end Chris Clemons due to a knee injury suffered against Washington in the playoffs.

Coach Pete Carroll said after the Seahawks were bounced by Atlanta in the second round of the playoffs that improving the pass rush was at the top of the priority list.

Seattle finished the regular season with 36 sacks, tied for 18th in the league. Eight of those sacks came in one game early in the season against Green Bay, and the Seahawks had just eight sacks over the final six weeks of the regular season.

Avril had 9½ sacks last season, but the best of his five years with Detroit came in 2011. Avril had 11 sacks — good for seventh in the NFC — along with six forced fumbles and an interception. He's started all 16 games in each of the past two seasons and his long, lean frame fits the specialized types of defensive ends that Carroll wants.

ESPN.com reported Avril's new deal is for $15 million over two years. The deal with Avril comes on the heels of Seattle making a big splash earlier this week when they acquired Percy Harvin from Minnesota in exchange for three draft picks.

Seahawks quarterback Russell Wilson tweeted Wednesday, "Welcome big man Cliff Avril. I luckily don't have to get chased around by you anymore!"

Not yet 27 years old, Avril was considered one of the top defensive line options on the free agent market. He was the Lions' franchise player last season, playing under a one-year deal that paid him $10.6 million. But he knew his future in Detroit was uncertain. Avril had 39½ sacks and 16 forced fumbles with Detroit after the Lions selected him in the third round of the 2008 draft.

"I would love to be here, but I know how this thing shakes out. I know how this works," Avril said after the season. "Just take it in stride."

Avril's acquisition gives security for the Seahawks should Clemons not be ready to go when the regular season begins. Clemons suffered a torn ACL in his left knee during Seattle's playoff win at Washington in January and there's been no timeline given on Clemons recovery.

Reaching a deal with Avril also reduces the need for Seattle to hit on a defensive lineman in next month's draft. The Seahawks took Bruce Irvin in the first round last year, but just sent their first-round pick this season — No. 25 overall — to Minnesota as part of the Harvin deal. The Seahawks still hold eight picks in April's draft.