* Atlantia 's board to meet again on Autostrade deal
* ACS values Atlantia's unit at 9-10 bln euros -TCI
* Atlantia shares end up 3.1% on ACS approach (Updates and recasts with Atlantia's statement)
By Francesca Landini
MILAN, April 8 (Reuters) - Spanish infrastructure group ACS ACS.MC has approached Atlantia ATL.MI about taking a stake in the Italian group's motorway unit, the Rome-based conglomerate said on Thursday.
The surprise move comes as Atlantia is engaged in advanced talks with a consortium led by Italian state lender CDP over the sale of its 88% stake in Autostrade per l'Italia.
Toll-road operator Autostrade, which manages half of Italy's motorway network, has been in the political crosshairs since the 2018 deadly collapse of a motorway bridge in Genoa that was run by the company.
Atlantia said its board on Thursday began looking at a revised offer sent last week by the CDP-led consortium but acknowledged the ACS group's interest.
"The board also noted the expression of interest, received today from the ACS group, in acquiring a stake in ASPI (Autostrade), in consortium with other Italian and international investors," Atlantia said in a statement.
According to Atlantia investor TCI, ACS sent a letter offering to buy a large stake in Autostrade at better conditions than the ones proposed by the CDP-led consortium.
The Spanish group values the whole unit at 9 billion to 10 billion euros ($10.7 billion-$12 billion) but has not mentioned any request for guarantees against legal risks, TCI said.
ACS declined to comment.
Shares in Atlantia closed up 3.1% on Thursday on news of ACS's approach.
Last week, CDP and its partners, Macquarie MQG.AX and Blackstone (NYSE:BX) BX.N , filed a binding bid based on a valuation of 9.1 billion euros for the whole of Autostrade and asked Atlantia to cover 870 million euros in potential legal risks, sources had said. said its board is expected to meet again in coming days to discuss Autostrade and take a decision.
The board also asked the group's financial advisers to explore the intentions of ACS, a source with knowledge of the matter said.
"We welcome ACS's offer, which is far superior to the offer made by (Italian state lender) CDP and its partners," Jonathan Amouyal, partner of TCI Advisory, told Reuters.
"The Italian government should allow Autostrade to be sold to the highest bidder without any political interference," he added.
The consortium's move on Autostrade has the backing of the Italian government, which has still to give its final blessing to a new tariff system scheme for the company and a settlement agreement with Atlantia over the bridge disaster.
In recent weeks some core investors in Atlantia, including the Benetton family, indicated their interest in clinching a deal with the consortium while other shareholders, including TCI have asked for better terms.
Back in 2017, ACS and Atlantia jointly acquired Spanish toll-road operator Abertis in a deal worth more than 16 billion euros. ($1 = 0.8401 euros)