By Gwénaëlle Barzic and Mathieu Rosemain

Elliott, which made waves in France last year when it revealed a stake in drinks maker Pernod Ricard, has since built a holding of more than 10% in Altran, regulatory filings show.

It has also said Capgemini's 3.6 billion (£3 billion)-euro bid from June this year undervalued Altran.

Capgemini CEO Paul Hermelin said in an interview that he believed the IT services and consultancy group would manage to get 50.1% of Altran shareholders behind the deal at the current offer price, which would not be altered.

"It will not change," he said, adding that Capgemini thought it was a fair value after having had access to Altran's books. "We saw things we liked and others we liked less."

Capgemini is hoping the deal will add to its services in industries from telecoms to aerospace, and bring large cost savings. Its offer represented a 22% premium to Altran's share price on the day it was announced.

The company has outlined a self-imposed threshold to get backing from just over half of Altran's investors. Below this point, Capgemini will let the deal go and study other acquisition targets, Hermelin said.

"At that stage we'd walk away and do something else," Hermelin said. "I have lots of other ideas. The digital industry is full of opportunities."

Hermelin said he was prepared to meet Elliott representatives to discuss the Altran deal, if they had something new to discuss.

Elliott declined to comment.

Capgemini's Altran takeover also faces other hurdles, such as legal challenges filed in Paris by representatives of Altran's minority shareholders, including Elliott, taking issue with some of the formalities around the deal.

A court hearing is scheduled for Dec. 4 to examine one of these claims, which could lead to Capgemini's offer being suspended, while a judge will also rule later on whether there were irregularities in the bidding procedure.

That decision is expected by the end of March at the latest.

"We'll see then what we do," Hermelin said.

(Reporting by Gwenaelle Barzic and Mathieu Rosemain; writing by Sarah White; editing by David Goodman and Jane Merriman)

By Gwénaëlle Barzic and Mathieu Rosemain