Both Maersk Line and CMA CGM have confirmed the delay, with Maersk saying it expects Chinese approval "mid-year".
The delay means P3 will not be able to take full advantage of this year's peak season. Cargo volumes typically surge in the middle of the year as Christmas merchandise is shipped from Asia to the US and Europe.
The vessel-sharing network of Maersk, MSC and CMA CGM has not received Chinese approval and discussions continue with the European Commission about possible regulatory snags the alliance might face.
While Washington has given its go-head, Beijing authorities are still weighing the P3 proposal. Brussels will provide no formal approval, but will allow the lines to self-assess if their dominant position is abusive.
With this in mind, P3 members are in talks with European Commission officials in hope of "having their blessing", AP Moller-Maersk CEO Nils Andersen told Lloyd's List.
There is also South Korea, Ukraine and Vietnam, which are thought to have competition concerns.