Christian Aid has welcomed the protection of overseas aid in the Chancellor's spending review.
The development agency said the Government deserved credit for keeping its promise to the world's poorest people despite the difficult economic climate.
Barry Johnston, Senior UK Political Adviser at Christian Aid said: "Morally it is the right thing to do and it costs the UK less than a penny in each pound of national income."
However, he said the spending review made it more difficult to understand why the Government has not brought forward legislation to safeguard the spending.
This, he said, would give countries receiving aid from the UK "a greater degree of certainty".
"While aid is a vital lifeline for them at present, in the longer term we want to see them able to stand on their own two feet," he said.
"This is why the Prime Minister and the Chancellor must complement their commitment to aid by maintaining the momentum on tax transparency built up by the promises made at the G8. Tax transparency holds the key to ending aid dependency.
"Rather than resting on their laurels, ministers must roll up their sleeves."
Caritas Social Action Network, the social action arm of the Catholic Church, voiced concerns about the impact of some proposed changes on people struggling or already living in poverty in the UK.
CSAN's Public Affairs Officer, Liam Allmark, welcomed the Government's commitment to preserve funding for the pupil premium, but questioned the cap on welfare spending, the 10% reduction in local government funding, and a change to conditions for claiming benefits, including making the jobless wait seven days instead of three before being able to claim.
"The further cuts in funding to local authorities are particularly worrying given the current trend in localising benefits. With Council Tax Support and Crisis Loans now being administered directly by local Councils at their discretion, we have serious concerns that vulnerable individuals could be left without appropriate support," he said.
"The proposed seven-day wait before jobseekers can claim benefits could cause severe financial hardship for families who are already trying to balance tight budgets and meet rent payments.
"Without robust safeguards in place, the requirement that claimants learn English has the potential to penalise some of the most vulnerable members of society."