* Bertrand Meunier steps down as chairman

* Sees sale of Tech Foundations to Kretinsky completed in Q2 2024

* Failure of sale to Kretinsky would lead to refinancing

(Recasts with Mustier's nomination; adds critics of Kretinsky deal in paragraphs 5,6; Atos seeking loan waivers in paragraph 11)

Oct 16 (Reuters) - Banking big-shot Jean-Pierre Mustier is taking over the helm of Atos' board of directors, the crisis-hit French IT consulting group said on Monday, driving the shares up as it seeks to secure a contested deal with Czech tycoon Daniel Kretinksy.

Mustier, a former CEO of Italian bank UniCredit, is replacing Bertrand Meunier, who has recently been the focus of criticism by several minority shareholders after Atos dropped an initial plan to split up the company into two listed entities in favor of selling its largest division to Kretinsky.

Mustier, credited with restoring UniCredit's capital strength, will be tasked to revive investors' trust after a governance crisis and a series of setbacks pummeled Atos' shares, now trading at near record lows.

Atos shares jumped by more than 20% in early Paris trading but reversed course in the morning. They were down by 1.6% at 0749 GMT.

The planned sale of Atos's loss-making legacy IT operations, dubbed Tech Foundations, to Kretinsky is opposed by some minority shareholders and several French politicians.

Critics of the deal with Kretinsky, who would secure more than half of Atos' activities in terms of sales, have said the transaction was too favorable to the Czech billionaire because it shielded Tech Foundations from Atos' total 2.3 billion euro ($2.42 billion) debt.

The two-part transaction, which also comprises a 900 million euro share sale for the remaining part of Atos, dubbed Eviden, would make the Czech tycoon the number one shareholder of Eviden, deemed a strategic asset by the French state.

Kretinsky has promised to remain a passive shareholder in Eviden. He has also said that he is open to selling part or all the 7.5% stake he would gain in Eviden, a source close to the matter said.

Kretinsky's aides have also insisted that the deal would transfer 1.9 billion euros worth of on-balance sheet liabilities from Atos as it stands now.

Atos on Monday reiterated the plan to sell Tech Foundations to Kretinsky under the terms announced in August, although it signaled some of the financial terms could change.

It said it now expected to complete the deal in the second quarter of 2024.

In the event of a failure of the deal with Kretinsky, Atos would have to consider the sale of additional assets or "access the debt and equity capital markets" to safeguard the liquidity of Atos, the company added.

The group, which secured a 2.7 billion-euro short term debt package to finance its transformation, said it was in active discussions with its financing banks to obtain loan waivers as 1.5 billion euros worth of the debt mature in January 2024.

($1 = 0.9499 euros) (Reporting by Mathieu Rosemain and Pierre John Felcenloben; Editing by Christian Schmollinger, Shri Navaratnam and Louise Heavens)