The Capital Markets Authority said it was studying the offer by Orange Participations, but gave no further details. A Mobinil spokesman declined immediate comment.
Mobinil, one of three mobile operators in the most populous Arab country, has been at the centre of a dispute between regional operator Orascom Telecom and France Telecom.
Egypt's market regulator had said that France Telecom should tender to buy all shares in Mobinil as part of a court ruling that it purchase Orascom's stake in a holding company that owns 51 percent of Mobinil.
Mobinil posted a 6 percent fall in net income last month for the first quarter of 2009 to 424 million Egyptian pounds ($75 million), missing most analysts' forecasts as it faced higher interest costs.
The Egyptian stock exchange said it had suspended trade on Mobinil shares until the markets authority finishes studying the offer. Shares had jumped more than 6 percent on Monday on speculation of a pending offer to end at 204.97 pounds.