LONDON, Aug. 24 (Xinhua) -- Premier League club Sunderland signed Scotland striker Steven Fletcher from Championship side Wolves on Friday.

Fletcher agreed a four-year contract after Wolves accepted an improved offer from Sunderland boss Martin O'Neill.

"It has been no secret that we needed to strengthen our attacking options and Steven has a proven track record of scoring goals," O'Neill told Sunderland's website.

Even though Wolves were relegated from the Premier League last season, Fletcher still impressed and got on the scoresheet 12 times.

He scored the same amount the season before, to make it 24 goals for the club in 45 starts.

That prolific form made Fletcher the top target for O'Neill as he looked to bolster his attack following the departures of Nicklas Bendtner and Asamoah Gyan.

"I'm delighted. I've just come from the training ground and I'm delighted it's all gone through," O'Neill added.

"I think Steven will be terrific for us. He's capable of scoring goals and linking play which is very important to us and I think now at 25 years of age he's got room to improve and really get better."