Atlas Arteria's (ASX:ALX) independent directors urged its security holders in its target's statement to reject an unsolicited off-market cash takeover offer by Diamond Infraco 1, a wholly-owned unit of IFM Global Infrastructure Fund, saying "it is opportunistic and materially undervalues Atlas Arteria," according to a Tuesday Australian bourse filing.

The directors' view was reinforced by the opinion of an independent expert, who concluded that the offer is neither fair nor reasonable.

The target's statement was sent to Diamond Infraco and lodged with the Australian Securities and Investments Commission on Tuesday. The bidder offered the security holders AU$4.75 in cash per ALX Atlas Arteria security, less any distributions paid by the firm.

Diamond Infraco expressed "strong disagreement" with the arguments brought forth by the independent directors of Atlas Arteria to support their recommendation that Atlas Arteria security holders reject the offer, according to its second supplementary bidder's statement.

It confirmed that the EU merger control regulatory approval condition, as stated in the bidder's statement, was satisfied.