Dutch outfit claim player has joined Gunners
The player is a graduate of the Rotterdam club's youth system but has now opted to move to the Emirates.
"We did what we could do by offering the kid a contract on time. But he wanted to wait, again this is his right. That he now goes to Arsenal, means that we only get a training allowance," Feyenoord technical director Leo Beenhakker said.
"This is the story of (Chelsea defender Jeffrey) Bruma, he was also a great talent that unfortunately never played for us. I treasure Ebecilio highly."
Chelsea were also rumoured to be interested in Ebecilio.