BERLIN (Reuters) - Insolvent German airline Air Berlin (>> Air Berlin Plc) said around 100 flight cancellations caused on Tuesday by large numbers of pilots calling in sick were threatening its existence and hurting its chances of saving jobs as it seeks investors for parts of the business.

"No company could possibly be seen in a worse light than Air Berlin today," Chief Operations Officer Oliver Iffert said in a internal memo to staff seen by Reuters.

"We must return to stable operations. That is crucial in order to bring talks with investors to a successful conclusion," he added.

The airline said around 200 pilots, mainly captains, had called in sick.

However, union Vereinigung Cockpit said in a separate statement it was surprised by the absences and that it had not called on its members to call in sick.

(Reporting by Klaus Lauer; Writing by Victoria Bryan; Editing by Maria Sheahan)

Stocks treated in this article : Deutsche Lufthansa, Air Berlin Plc