South Korean midfielder Ki Sung-yueng has signed a new four-year contract with Premier League side Swanse following an impressive start to the season.

Ki had a year left on his old deal after arriving from Celtic for what was then a club record £5million (6.3million euros) in 2012.

"I'm very pleased," 25-year-old Ki told the club's official website.

"This is what I have wanted to do - my first option was always to renew with Swansea.

"I want to sacrifice myself for the team and, as always, do as much as I can to help this team improve.

"I will be giving 100 per cent, and I am looking forward to continuing my work with the club."

The new deal is in stark contrast to Ki's early days in South Wales when he struggled to make his mark.

Despite making 38 appearances in his first season at Swansea, Ki was loaned out to Sunderland for the 2013-14 season, helping the Black Cats to a League Cup final appearance as well as winning their battle against relegation.

Sunderland and Aston Villa were both keen on securing Ki's services on a permanent basis but the 25-year-old has once more established himself under Swansea boss Garry Monk.

Ki scored his first goal for the club in Swansea's opening-day victory over Manchester United at Old Trafford and has been impressive as Monk's men have won their first two Premier League games.

"This team has a great potential, and I am sure that we will be amazing as time goes by," said Ki.