The 19-year-old Nigerian prospect was a January target for Celtic, with Eupen rejecting a £1million from the Scottish club.
Onyekuru was keen to move Celtic and decided to go AWOL for several days in hope of pushing the deal through, but the teenager has since returned to the fold and has been told he can leave the Belgium club at the end of the season.
However, Eupen will want nothing less than £6million for Onyekuru this summer, according to the Daily Mail.
Sevilla, Borussia Dortmund, Borussia Monchengladbach, Lille have all sent scouts in recent weeks to watch the youngster in action.
Arsenal, along with Chelsea, are now believed to be keeping tabs on Onyekuru’s progress ahead of a possible summer offer.
Oneykuru has netted 12 goals in 26 games for Eupen so far this season.