Egypt's financial supervisory authority has given Orascom Telecom a one-week deadline to divulge more details of its deal with France Telecom over ECMS.
France Telecom and Orascom reached an uneasy truce last month over the ownership details of ECMS, majority owner of mobile operator Mobinil, following a lengthy dispute.
But Egypt's regulator is demanding more disclosure, and has warned Orascom it could face sanctions if it does not comply, WSJ.com said.
Sanctions could range from stopping trading on Orascom stock to more drastic measures.
But the regulators did praise the parties for finally reaching an agreement, and said it won't appeal a court verdict blocking its decision to approve France Telecom's offer to acquire ECMS once a settlement has been reached.
The group have revised their shareholder agreement covering ECMS to give Orascom the option of combining its Mobinil and ECMS shares in the future.
As part of the agreement, France Telecom has agreed to pay €226 million to help settle the dispute.