Christian Aid has today warned the UK government not to 'play politics' with overseas aid in a way that harms the poorest.

The charity was responding to a speech this morning by Penny Mordaunt, secretary of state for international development, who said profits from development projects should be offset against the 0.7 per cent of national income Britain is legally committed to donating in overseas aid.

She also said private investment could 'make aid money work twice as hard'.

Mordaunt made it clear her plan was aimed at 'reducing the ask on the public purse'.

At present, finessing Britain's aid contribution in this way would be against international rules.

Christian Aid said the suggestion that private sector investments could replace rather than supplement public aid and still be effective at addressing poverty is 'wrong' and that any attempts to play politics with the aid budget 'will raise questions about how aid policy is being developed and in whose interests'.

The charity's director of policy and public affairs Christine Allen said: 'Publicly funded support for the most vulnerable is a hallmark of a civilized society.

'Private investment is also needed but is much less likely to reach the most vulnerable communities in the poorest countries. Suggesting that private sector investments, which have to make a return for investors, could replace rather than supplement public aid and still be effective at addressing poverty is wrong.'

She added: 'Aid has been marred for years by donor countries putting their own priorities, and those of private sector actors, ahead of the needs of the countries and people who should benefit from that aid. This distorts the purpose of aid and while there may be some areas of overlapping interests, progress does not always involve "win-wins".'

Kate Osamor, Labour's shadow international development secretary, told the BBC: 'This is an outrageous distortion of the country's overseas development programme.'

She said: 'The Tories' plans to rewrite the international rules on aid and slash billions of pounds of public money will do nothing to end global poverty or reduce inequality.'