* Brisa target of 2.66 euro/share takeover bid
* Shareholders with 15.68 percent want independent review
* Legal and regulatory battle looms (Adds details, background)
By Carlos Ruano
MADRID, June 5 (Reuters) - Spanish motorway firm Abertis and other shareholders of Portugal's largest highway operator Brisa have teamed up to fight a 700 million euro ($875 million) takeover bid they say is too low.
Abertis and shareholders, with a total 15.68 percent of Brisa, want Portuguese stock market regulator CMVM to appoint an independent expert to determine a fair price for the company, which is the target of a 2.66 euro-per-share offer by other leading shareholders.
"We consider the offer to be inadequate and to clearly undervalue the company, and are concerned with the process followed by the board of directors of Brisa in the assessment of the conditions and merits of the offer," the shareholders wrote in a document dated June 4.
The document is signed by Abertis, Franklin Templeton Investments, State of New Jersey Department of the Treasury Division of Investment and Cygnus Europa Event Driven Sub Fund.
The bid launched in March by Portugal's Jose de Mello and Arcus European Infrastructure Fund through Tagus Holdings, which holds 53.8 percent of voting rights in Brisa, offers a 13.4 percent premium for the company.
Brisa's shares, which were trading 1 percent higher at 2.48 euros on Tuesday, had lost 51 percent of their value in the 12 months before the takeover bid.
Abertis has warned that it may take legal action against Tagus Holdings and has hired Goldman Sachs as its advisor. ($1 = 0.8003 euros) (Writing by Tracy Rucinski; Editing by Erica Billingham)