(This December 27 story corrects number of job cuts to 900 not 90)

MILAN (Reuters) - Workers at BNL, the Italian arm of French banking group BNP Paribas (OTC:BNPQY), went on strike for the first time since the 1990s on Monday in protest at back office and IT staff cuts.

Italian banking unions said the strike was "a great success", adding that take-up had been solid.

"The bank's internal offices were completely deserted and remained closed as did most branches," Fabi, First-Cisl, Fisac-Cgil, Uilca and Unisin said in a joint statement.

BNL said that 29.8% of its employees joined the strike.

"In such context, which is also characterised by year-end holidays, BNL has nevertheless ensured business continuity by strengthening the digital channel to support the physical channel" it said in a statement.

Workers are protesting against BNL's decision to use external providers for IT and back office services, a move that unions said affects 900 out of a total of 11,500 BNL employees in its central offices and around 700 branches across Italy.

Unions have also voiced grievances about BNL's sale to Worldline of an 80% stake in its card payment processing business Axepta Italy.