Chancellor George Osborne has promised that the science budget will be protected in "real terms" over the next parliament.

As part of his Comprehensive Spending Review, Osborne said the annual science budget would rise to £4.7bn by 2020 – an increase of £500m in total over four years. A further £6.9bn will be invested in science and innovation capital, he said.

Full details of what the science budget covers and what new activities have been "tucked-in" are not yet known, although a proportion of overseas aid related research is one likely addition.

The chancellor also announced a raft of departmental cuts that will impact UK science. Funding for the Department For Business, Innovation and Skills is due to be cut by 17%, Defra's budget will fall by 15%, and the Department for Energy and Climate change will be cut by 16%.

Responding to the Chancellor's speech, the Society's chief executive, Mark Downs, welcomed the pledge to protect science spending.

"Science research and development is a clear engine to rebuild and grow the economy and to provide the societal benefits in which people want to invest.

"We welcome the fact that the Chancellor and ministers have listened to the science community, recognising that backing science backs business and supports society, by offering to protect science funding in real terms. The community will be examining the full implications of the Chancellor's plans including the impact of departmental settlements and the scope of the science budget, and developing our response."

Ahead of the review, Downs joined other science leaders in issuing strong calls for investment in research, including writing to and meeting ministers. The campaign group Science is Vital, a group of 'concerned scientists, engineers and supporters of science' held a rally in London calling for an end to 'destructive levels of cuts' to science funding in the UK.

The Government's previous budget protected the science budget but only in 'cash terms', meaning its actual value was eroded by inflation.