Chelsea have confirmed that an agreement has been reached with Borussia Monchengladbach for the transfer of attacking midfielder Thorgan Hazard on a permanent deal for a fee of around £5.8 million.

The 21-year-old signed for the Blues in 2012 for £366,539 alongside his brother Eden but was farmed out immediately to Belgian side Zulte Waregem where he spent the following two seasons on loan.

He then joined the Die Fohlen in August on a season-long loan deal but Gladbach have now secured his services until 2020 for a fee believed to be around the region of £6million.

However, Chelsea have inserted a buy-back clause into the contract and declared on their official website that they will continue to “monitor his progress”.

Hazard said: “I signed here for four years plus one year optional, because I think Borussia is the right club for me to keep growing. It is too soon for me to play for Chelsea.

“Borussia is a club that suits me perfectly. Monchengladbach is not far from Belgium and the club has great fans that always support us. They are a good team, have a good coach and it is a good place for me to develop.”

Gladbach sporting director Max Eberl added: “Thorgan has already shown that he is a huge talent. We’re happy we have managed to sign him on a permanent basis and that he has decided to play for Borussia in the coming years.”

Hazard never made a first-team appearance for Chelsea.