Innogy CEO says losing staff due to split-up fears

* Staff leaving group, CEO says

* Staff need assurances about future

* Innogy Q1 adj net down almost 11 pct

* Npower unit's adj EBIT up 26.5 pct (Recasts, adds quotes from conference call)

By Christoph Steitz and Tom Käckenhoff

FRANKFURT/DUESSELDORF, May 14 (Reuters) - Innogy CEO Uwe Tigges acknowledged on Monday that staff are leaving ahead of a merger that will see parent RWE (IOB: 0FUZ.IL - news) and rival E.ON split up the German energy company.

"Yes, it is something we are observing," Tigges said, not giving any numbers but underscoring the importance of assuring senior staff and younger talent about their future prospects.

"If that's not the case it'll really be difficult for us in the next months," he added.

The deal to split up of Innogy's renewables, networks and retail operations has sparked fears among management and workers, who fear they might have to bear the brunt of up to 5,000 job cuts E.ON is planning as part of the asset swap.

The deal, which will take place in several steps due to its complex structure, is expected to close in the second half of 2019.

Innogy, RWE and E.ON last week agreed with unions to cut jobs in a socially responsible way, a step that Innogy said went in the right direction.

The group pointed out, however, that legally binding commitments for certain demands it has made had not been reached, including retaining its brand, Europe's fourth most valuable utility brand.

German carmaker Opel recently said it had suspended voluntary redundancies to stop skilled workers from leaving the group in the wake of French car group PSA's acquisition of the brand last year.

Innogy on Monday reported an adjusted net profit of 610 million euros ($731 million) for the three months to March 31, down almost 11 percent from a year earlier.

Its British division Npower saw operating profit rise 26.5 percent ahead of a planned merger with the local retail power unit of SSE (LSE: SSE.L - news) aimed at challenging top utility British Gas .

The deal would rid Innogy of its most problematic unit, which has lost customers in recent years due to billing issues and growing competition.

A week ago, British regulators launched an in-depth investigation into the proposed tie-up, saying it may reduce competition and increase prices for some households.

($1 = 0.8348 euros) (Editing by Ludwig Burger and Jason Neely)