"Elliott urges the Company to announce a new CEO without further delay and, once appointed, invites the new CEO to commence a strategic review in which all options to enhance stakeholder value should be considered," Elliott, which holds about 5 percent of shares in GEA, said in a statement on Monday.

GEA, whose machines are used to make milk products, instant coffee, and chicken nuggets, is struggling to win back investor support after cutting its profit targets in both 2016 and 2017.

Chief Executive Juerg Oleas, who said in March he would not stand for another term, has initiated a restructuring plan but the measures taken so far will take around two years to gain traction, which is too long for some investors.

Oleas is due to stay on until early 2019. In addition, GEA's finance chief Helmut Schmale agreed in April to take early retirement.

"By acting decisively and swiftly in the wake of the recently announced departures of its CEO and CFO, and getting the right leadership and governance in place, GEA can regain its investors' trust and avoid a lengthy period of business drift and market uncertainty," Elliott said.

It also said GEA should refresh shareholder representation on the supervisory board, including by replacing Chairman Helmut Perlet, to combat what it said was excessively long board tenure and a disconnect between executive pay and GEA's performance.

GEA should also launch a substantial share buyback, Elliott said, saying that its liquidity profile and low share price had created a good opportunity to return cash to shareholders without risking GEA's investment grade credit rating.

GEA's stock has lost 29 percent of its value so far this year and is down more than 40 percent from a record level of 50.17 euros reached in August 2016.

Elliott last month raised its stake in GEA to just over 5 percent from 3 percent, making it the fifth-biggest investor behind Kuwait Investment Office, MFS Investment Management, Blackrock, MFS Investment Management and Albert Frere.

(Reporting by Christoph Steitz and Anneli Palmen; Writing by Maria Sheahan; Editing by Tom Sims and David Evans)