LONDON (Reuters) - TSB, the UK banking arm of Spain's Sabadell, is seeking 250 job cuts and 36 branch closures, a spokesperson for the bank and employee union Unite said on Wednesday, as the lender accelerates a restructuring push to save costs.

The likely redundancies are expected to fall in the bank's fraud operations, central operations and across TSB's branch network, Unite said, adding that it would seek talks with management in an effort to reduce any additional layoffs.

The proposed job losses come just three months after TSB announced plans to cut around 300 roles in its Risk & Finance, Customer Banking and Customer Delivery teams on February 6.

"To meet changing customer needs and for TSB to remain competitive, we are making changes to simplify the way we operate," the bank spokesperson said in a statement on Wednesday.

"These decisions are never taken lightly. Our priority is to consult with impacted colleagues to ensure they're fully supported, maximising redeployment opportunities where we can."

Unite regional officer Andy Case described the bank's plans as a "grave mistake".

"These workers perform essential work in the fraud departments and across the branch network. TSB customers will rightly be concerned by today's news and they will undoubtedly suffer a downgrade in service from these job cuts."

Sabadell itself has just turned down a takeover offer from larger Spanish rival BBVA

(Reporting By Sinead Cruise; Editing by Amanda Cooper)