Trade union Unite is writing to Royal Bank of Scotland to express its anger over renewed speculation of thousands of job cuts at the part-nationalised lender.

Unite is disgusted that the workforce of RBS has today read in the media that further job losses are being considered. This constant speculation and rumour is highly concerning for those who work for RBS, Unite national officer David Fleming said in a statement on Thursday.

Unite is today writing to management to call on them to engage with Unite ... on their plans for RBS in the UK, he added. It is vital that they develop a strategy for saving jobs at all levels.

RBS, which is 83 percent owned by the government after a state bailout during the 2008 credit crisis, is planning to scale back its investment banking arm, and the Financial Times reported that some 10,000 jobs could be cut.

However, an RBS spokesman said the report of 10,000 job cuts was inaccurate but declined further comment.

A source with knowledge of the matter told Reuters this week that RBS had hired investment bank Lazard to advise it over its scale-back of the RBS investment banking division.

RBS had already announced last year cutbacks to its investment banking division and plans to axe more jobs at the unit.

It came under further pressure to rein in the business, known within RBS as GBM (Global Banking & Markets), in December when Chancellor George Osborne told RBS to make further significant reductions.

The Scottish bank's GBM unit is strong globally in bond trading, foreign exchange and American mortgage financing.

But it is outside the global top tier and is expected to scale back in equities -- potentially selling its UK advisory and broking business Hoare Govett -- as part of a retreat that could again cut its size in half, bankers and analysts have told Reuters

(Reporting by Sudip Kar-Gupta; Editing by David Holmes and Elaine Hardcastle)