Political fury was mounting today after it was revealed that the taxpayer-owned banks Lloyds and Royal Bank of Scotland have pumped almost £2.8 billion into their Irish offshoots over the past 10 months.

RBS's Ulster Bank (ROI) has received four capital injections totalling some £1.44 billion while Lloyds' Bank of Scotland (Ireland) has received two injections totalling £1.32 billion. The capital injections are largely needed to bail the Irish subsidiary banks out of bad loans made to Irish property developers at the height of the Celtic tiger boom. Many of those loans have had to be written down heavily.

Vince Cable, Liberal Democrat Treasury spokesman, said: “Many will find it hard to understand why British taxpayers are bailing out bad investments made in Ireland. This clearly shows that these banks are far from out of the woods.”

And Brian Lucey, finance professor at Trinity College, Dublin, said: “The scale of the figure is quite shocking. These were not leaders in the Irish market. The figure just shows the level of clean-up needed.”

The taxpayer holds a 70% stake in RBS — which got a £20 billion bail-out — and a 43% stake in Lloyds which received £17 billion.

UK Financial Investments which manages the Government's stakes in the banks told Bloomberg News that it would “not intervene in operational management decisions”.

RBS and Lloyds could not comment on whether the two banks expect to have to transfer further capital to their Irish businesses.