LONDON (Reuters) - Lehman Brothers's "exceptionally complex" structure makes it hard to predict how its European creditors will fare, the joint administrator for the bank's European operations said on Monday.

Tony Lomas, a partner at PricewaterhouseCoopers who was appointed joint administrator for Lehman Brothers International Europe on Monday, said he was amazed the New York-based bank collapsed late on Sunday.

"I am surprised. It seems amazing that a business as huge as this can fail in this way," Lomas said at a news conference.

"What it underlines for me is the massive importance of market confidence. Once that's gone and nobody wants to trade with you, you're in serious trouble ... there's no way back."

There is no guarantee Lehman's European staff will be paid at the end of this week. After the U.S. bank's collapse, there was no cash in the European arm and it is not clear where they are ranked as creditors, Lomas said.

He could not say how many of Lehman's 6,000 European staff will lose their jobs or whether bonuses would be paid.

Lehman's market activity was suspended early on Monday as the administrators needed to assess counterparty risk. Some trading could resume, but new commitments in the market were likely to be "negligible", Lomas said.

(Reporting by Douwe Miedema and Steve Slater; Editing by Paul Bolding)