Cases of children being sexually abused by aid workers are among a batch of 80 incidents reported to a watchdog in the past three weeks.
Charities have told the Charity Commission about a wave of current and historical "serious" cases of people being harmed or put at risk of harm since February 12.
The reports, which span 26 organisations, include allegations or incidents of sexual abuse of staff, volunteers and beneficiaries, including children, the commission said.
Seven of the organisations came forward with cases that have been reported since April 2017.
Some reports of historical allegations of abuse or harassment were made after the sector came under the spotlight in the wake of the Oxfam sex scandal.
The commission said the number of serious incidents being reported had doubled in recent weeks.
On average the watchdog receives around 50 reports of serious incidents across a range of issues per week, including finance and governance, but is now dealing with about 100.
Penny Mordaunt said it was a "wake-up call" for the sector and warned it must act to restore its credibility with the public.
Speaking at a safeguarding summit in central London, the International Development Secretary warned predators exploiting the aid sector there is "no hiding place".
"We will find you, we will bring you to justice. Your time is up," she said.
Ms Mordaunt wrote to 179 aid charities and organisations after it emerged there were widespread concerns about the behaviour of aid workers and the way they were being dealt with.
All have responded and given statements of assurance about the way they operate, but 37 still have questions to answer, the summit heard.
The Department for International Development has also carried out an internal audit and the findings are expected to be released on Monday.
New standards have now come into force that aid organisations must meet to be eligible for Government money.
Baroness Stowell, the newly appointed chairwoman of the Charity Commission, told the summit had "intensified" its efforts to deal with safeguarding incidents.
She said: "If we are to restore public trust, we must understand why people are angry and it's the same thing that has affected the corporate and political worlds too - important institutions acting in the interests of those in charge, rather than of the people they exist to serve.
"It's bad enough when bankers disappoint. But when aid workers and charity bosses are self-interested it is incomparably worse."