A spokeswoman said the investigation was a matter of course, to see if there were any concentrations of business that could breach competition rulings.
A decision is expected by 10 October, but any over-concentration of business could prompt an enquiry.
Buhrmanns corporate communications director, Ewold de Bruijne, said: PaperlinX is operational in a number of countries where we also operate, but we do not foresee any problems. He still expected the deal to be completed in the fourth quarter of this year.
PaperlinX has offered 522m for Buhrmanns paper merchanting division.
Have your say in the Printweek Poll
Related stories
Latest comments
"Wow, amazing achievement, congratulations Lance, you are without doubt the most awarded person in the industry. Fair play. That trophy cabinet must be busting at the seams ;)
Congratulations again."
"No Mr Bond, I expect you to di-rect mail"
"I'm sure this will go down well with print supply chain vendors. What terms is it that ADM are after - 180 days is it?"
Up next...

Merchandise key to growth, MD says
Visual Print and Design expands premises, adds merch showroom

Easy way to add new products
Snuggle offers new trade DTF service

25-year relationship with HP
Swype makes super swap with HP 7900 install

Includes 'next-level personalisation'