VIENNA (Reuters) - Raiffeisen Bank International AG (>> Raiffeisen Bank International AG) raised its forecast for 2013 bad loan provisions on Sunday, citing developments at its corporate customer business.

Emerging Europe's second biggest lender had previously guided for a net provisioning need at a similar level to the just over 1 billion euros it booked in 2012. Now it expects an increase to between 1.1 billion and 1.2 billion euros (919.16 million pounds-1 billion pounds) this year, it said in a statement.

"The revision is based predominantly on the development of the Corporate Customer business in the segments Group Corporates, Central Europe and Southeastern Europe," it said.

"The rest of RBI's outlook is confirmed," it added.

Raiffeisen in August had forecast flat lending volume, a slight increase in its net interest margin, and a flat or slightly higher cost base in 2013.

That was when new Chief Executive Karl Sevelda said Raiffeisen would adopt "painful" cost cuts that include forced lay-offs, reining in the empire that he took over in June.

Peers including Erste Group Bank (>> Erste Group Bank AG) and UniCredit Bank Austria (>> UniCredit SpA) have also had to boost bad loan provisions as economies in central and eastern Europe struggle.

(Reporting by Michael Shields; Editing by Robin Pomeroy and Mike Collett-White)