Source: Omnisport
1 May 2015 - 5:19 AM UPDATED 3 HOURS AGO
Lokeren announced the news on Friday (AEST), expressing its sadness at the death of the 24 year-old Belgian, who suffered heart failure.
Mertens, who represented Belgium at youth level, collapsed after 15 minutes of Lokeren's match with Genk.
He received CPR on the pitch and was placed on a life support machine in hospital.
"Despite the good medical care of our own sports staff and colleagues in Genk, it soon appeared the situation was very serious," a Lokeren statement read.
"Gregory was revived on the field and transferred to the hospital in Genk. Medical staff have done everything they could to save Gregory, but they finally had to acknowledge their impotence.
"Today, Gregory died at around 1630. His family were able to say goodbye."
Mertens joined Lokeren from Cercle Brugge last year and played 101 Belgian Pro League games.
"Much too soon, we say goodbye to Gregory Mertens," the club statement added.
"We are a football club. Everyone in and around the club breathes football. But suddenly something happens which we realise that football is just football. Today is such a time.
"Now we will have to learn to live with the loss.
"We realise that this is mainly for the family are incredibly difficult moments. We already offer them in the name of the whole club our sincere condolences."
England youth international Fabrice Muamba, who survived after suffering a cardiac arrest on the pitch at White Hart Lane while playing for Bolton Wanderers against Tottenham Hotspur in a March 2012 FA Cup tie tweeted:
Horrible news that Gregory Mertens has passed away, only 24 years old. #RIP
— fabrice muamba (@fmuamba) April 30, 2015
Football players and supporters everywhere will feel your loss. RIP. OM
