LONDON -- The chief operating officer at Barclays, which has recorded $3.18 billion in write-downs from the global credit crisis, will step down later this year, the bank said in a suprise statement today.

Barclays PLC, Britain's third largest bank, denied media reports of a rift between senior executives at the bank and COO Paul Idzik, saying he was leaving to seek new challenges.

Idzik, who joined the bank in 1999, played a key role changing the bank's culture and management with chief executive John Varley.

His resignation comes at a critical time for the bank, which has suffered sharp profit declines because of global market turmoil.

Analysts have speculated that Barclays would follow HBOS PLC and Royal Bank of Scotland Group PLC in announcing new shares to raise capital to offset losses from the U.S. subprime crisis.

Shares in the bank rose 2 percent higher to 474.5 pence ($9.43; 6.07 euros) today.

Varley said Idzik had played a "key role" in consolidating and expanding investment banking and asset management, as well as creating the global retail and commercial banking business.

"It is what I brought him in to do, and that part of our work is substantially complete," Varley said in a statement. "As such, Paul has decided that this is the right time to look for his next challenge."

Idzik said he looks "forward to identifying and pursuing my next challenge."