Executive vice-president and company group chairman Ryan Weldon will leave, Valeant confirmed late on Friday after inquiries by Reuters. Like Chief Executive Mike Pearson, Weldon previously worked for management consulting firm McKinsey & Co.

Valeant said Weldon's departure was planned, and takes effect after it completes a $1.4 billion sale of several injectable treatments to Nestle SA. The sale was made to allay potential anti-trust concerns about Valeant's takeover bid for Allergan.

"Although his leadership will be missed, the company has created and developed a strong management team and I am confident Ryan will assist us successfully through this transition period," Pearson said in a statement.

Weldon called his six years at Valeant "extraordinary" and said it was a privilege to work with Pearson and the rest of the company.

Weldon exits as Allergan has criticized Valeant's "significant management turnover" and accused the Laval, Quebec-based company of lacking the experience to manage complex global businesses.

In a May 27 investor presentation, Allergan said that of the current management team, only Pearson and general counsel Robert Chai-Onn were in executive officer positions three years ago.

Pearson answered that criticism and others the next day, in a 3-1/2 hour meeting with investors and analysts in New York.

"We make those changes through people that we bring in through our acquisitions, we go outside for key talent and we continue to look to upgrade the talent," Pearson said. "We think this is a strength, not a weakness in terms of our business model."

Valeant and its ally Pershing Square Capital Management - Allergan's biggest shareholder - have offered to buy the Botox maker for $53 billion in cash and shares. Allergan has rejected the offer and refused to negotiate, leading Pershing to move toward replacing most of Allergan's board at a special meeting.

Valeant's Toronto-listed stock has fallen nine consecutive sessions, losing 12 percent since touching a three-week high on May 30, when it made its most recent revised offer for Allergan.

Talk circulated last week that ValueAct Capital Management, one of Valeant's biggest shareholders, was selling its stock, but ValueAct was quoted by Bloomberg on Friday saying this was not true.

California-based Allergan has lost ground in seven of the last nine sessions.

(Reporting by Rod Nickel in Winnipeg, Manitoba and Olivia Oran in New York, editing by David Evans)

By Olivia Oran and Rod Nickel

Stocks treated in this article : Allergan, Inc., Valeant Pharmaceuticals Intl Inc, Nestle SA