MILAN, Oct 21 (Reuters) - Any vote by shareholders in October in favour of the spin-off of the Italian motorway assets of Atlantia could be set aside if an attractive offer from state lender CDP or other suitors came along, proxy advisers said.

In reports prepared for the infrastructure group's shareholder meeting on Oct. 30, Glass Lewis and ISS recommended investors vote in favour of a plan to spin off the group's 88% stake in Autostrade per l'Italia.

But they also said such a move could subsequently be undone.

"Shareholders should be aware that even if the demerger is approved, the company may still opt to pursue a sale of its entire interest in Autostrade to CDP and/or other investors," Glass Lewis said.

Atlantia is currently in talks with a consortium comprising CDP and investment funds Macquarie and Blackstone regarding the potential sale of its entire stake in Autostrade.

On Tuesday the group said it would give the CDP-led consortium until Oct. 27 to improve its bid.

"If (the Atlantia) board determines that the terms of such a sale are more favourable than the proposed separation, the board may call a separate meeting at a later date to seek shareholder approval to revoke this proposal," Glass Lewis said.

Proxy adviser ISS also said "a sound offer" for the 88% stake in Autostrade could prompt it to urge investors to revoke any shareholder approval on Oct. 30.

Atlanta has been embroiled in a legal dispute with Rome since 2018, when a bridge run by Autos collapsed killing 43 people. The government has threatened to strip it of its motorway licence.

A deal seemed close in July when Rome approved a plan under which Atlanta would cede control of Autos to CAP. But talks floundered, prompting the group to press ahead with plans for a demerger.

Last week, CAP and Atlanta began exclusive talks to try to break the deadlock. (Reporting by Francesca Landini; editing by Emelia Sithole-Matarise)