Britain's government initially estimated the price of the pope's four-day visit - which saw the pontiff address crowds in London, Scotland and central England - at 10 million pounds, excluding security costs. Officials said Thursday that the final tally will be lower, and is likely to be confirmed to Parliament next week.
Malcom Bruce, chairman of Parliament's international development committee, said the revelation that development funds helped finance the trip will come as a surprise lawmakers and taxpayers.
"Ministers need to explain exactly what this (money) was spent on and how it tallies with our commitments on overseas aid," Bruce said.
Details of the spending came to light in a report from a committee inquiry into the accounts of Britain's Department for International Development. Bruce said lawmakers and taxpayers want to know if paying for part of the pope's September visit met global aid rules.
A spokesman for the Department for International Development said the money transferred to the Foreign Office did not constitute official development assistance and was part of a cross-departmental funding effort.
"Our contribution recognized the Catholic Church's role as a major provider of health and education services in developing countries," the spokesman said, noting that the committee also welcomed the agency's concentration on fragile states.
"The committee acknowledges that we are right to focus on conflict-ridden countries, home to some of the world's poorest people," he said, speaking on customary condition of anonymity.
The committee's report, however, also cautioned that giving such countries priority for aid means it will be difficult to ensure aid money is well spent in environments that frequently suffer corrupt and incompetent governments.
Well-run countries where aid money might prove more effective were bound to lose out as a result, the committee found.