Ministers must keep a closer eye on how international aid organisations spend UK cash, a committee of MPs has concluded.
The International Development Committee said not enough work was done to compare the value-for-money gained by the UK giving aid directly to a country through a bilateral arrangement, compared to sending it via a third party.
The Government monitors such arrangements through multilateral aid reviews (MAR), which look at 39 organisations which receive British money.
But committee chair Sir Malcolm Bruce said in 35 of those cases, a comparative value-for-money study was not completed.
He said: "It is in everybody's interests for the Government to make informed decisions about aid spending.
"When the UK provides funding to an international organisation, we need to have some assurance that this is better value-for-money than the alternative. Comparing international organisations' work with our own bilateral aid programmes is imperative."
More visits should also be carried out to countries receiving aid on a multilateral basis, the committee said, after the 2011 MAR included only two visits to recipient countries.
In 2012, some 42% of Department for International Development's (DFID) budget was spent via international aid organisations.
Sir Malcolm added: "In countries where the UK has no bilateral aid programmes of its own, monitoring multilateral organisations is a key challenge for the Government. This is an extremely important issue, and we will return to it in our ongoing inquiry into the future of UK development cooperation.
"For a number of multilateral organisations, the UK has a seat on the board, which obviously provides us with some oversight. Nevertheless, we feel strongly that for the next MAR, the team should undertake more visits to countries in which the UK has no bilateral programmes."