Atlas Arteria (ASX:ALX) said an unsolicited takeover offer from IFM Global Infrastructure Fund will not open before May 11 at the earliest, and once it does, it will remain open for at least a month, according to a Friday filing with the Australian bourse.

IFM owns about 35% of the issued shares of Atlas Arteria and has proposed to acquire the remaining interest at AU$4.75 per share in cash. The price may increase to AU$5.10 per share if IFM obtains at least a 45% interest before the offer closes.

In a letter to its shareholders, Atlas Arteria warned that the proposal is subject to many conditions that might not be satisfied. It also cautioned that shareholders would receive the lower price if IFM's relevant interest threshold is not achieved prior to closing.

Atlas Arteria has created an independent board committee to evaluate the proposal and will provide a recommendation to shareholders in due course, it said.