Ange Postecoglou has reportedly made his eighth signing of the summer less than week after securing the services of Aaron Mooy and Mortiz Jenz.
Former BBC journalist Fraser Fletcher reports the Bhoys have brought in highly-rated West Ham youngster Justin Osagie.
He joins the Hoops on a permanent deal for the Hammers and can play both as a centre-back and as a midfielder.
The 17-year-old, who is eligible to play for Nigeria and England, is likely to feature for the Celtic B Team in the immediate future as Tommy McIntyre's side once again compete in the Scottish Lowland League.
The defender started his career at Southend, before being part of the Tottenham youth academy and then ultimately joining the West Ham set up.
He has never made a first team appearance for the London club.
Despite Hammers manager David Moyes giving numerous young players a chance last season, Osagie never featured.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here