Speaker Sir Lindsay Hoyle told MPs on Tuesday the Tory rebel amendment on overseas aid “may not be debated” on Monday as it is “outside the scope of the Bill”.
The decision means Boris Johnson has dodged a potential House of Commons defeat, with the organiser of the Bill, Tory MP Andrew Mitchell insisting it would have passed.
He said: “The government frontbench is treating the House of Commons with disrespect.
“They are avoiding a vote on the commitments that each of us made individually and collectively at the last general election, on a promise made internationally, and in the opinion of some of Britain’s leading lawyers the government is acting unlawfully.
“Had we secured a vote on the new clause, I can assure the House it would have secured the assent of the House by not less than a majority of nine and probably of around 20 votes.
“In the week of the British chairmanship of the G7, the government’s failure to address this issue will indisputably mean that hundreds of thousands of avoidable deaths will result.”
The planned rebellion was set to be backed by at least 30 Conservative MPs, including former prime minister Theresa May.
It followed the announcement last year the amount of money spent on overseas aid would be cut from 0.7 per cent of gross national income to 0.5 per cent, a decision that breaks a Tory manifesto pledge.
The Speaker explained: “As we all know, the government has, through our standing orders, significant control over the business the House considers on any given day, and its control is particularly strong when it comes to the initiation of public expenditure.
“Up ’til now, however, the House has not had an opportunity for a decisive vote on maintaining the UK’s commitment to the statutory target of 0.7 per cent.
"I expect that the government should find a way to have this important matter debated and to allow the House formally to take an effective decision.”
The Speaker said he was open to hearing applications for an emergency debate, which is now expected Tuesday.
Downing Street earlier hinted that aid spending could exceed the downgraded target when the donation of coronavirus vaccines is taken into account.
The Prime Minister’s official spokesman said: “You can expect the PM to set out more details at the G7 this week on the UK’s plans to share surplus doses with developing countries.
“As is standard, any funding that benefits poverty reduction in developing countries would count as ODA (Official Development Assistance) funding.”
Labour’s shadow foreign secretary Lisa Nandy earlier labelled the cuts “short-sighted” and not in Britain’s interest.
She said: “The government is making a real mistake. They’re about to go into the most important week in many, many months, the G7, with a major plank of global Britain in tatters.
“It’s short-sighted, it’s not in Britain’s interest and he could solve this very quickly.”