The new coronavirus pandemic is clearly "accelerating", the World Health Organization warned, but said it was still possible to "change the trajectory" of the outbreak.
The remarks came as the number of deaths soared past 15,000, with more than 341,000 people infected worldwide, according to a tally compiled by AFP from official sources.
"The pandemic is accelerating," WHO chief Tedros Adhanom Ghebreyesus told journalists in a virtual news briefing.
He said it took 67 days from the beginning of the outbreak in China in late December for the virus to infect the first 100,000 people worldwide.
In comparison, it took 11 days for the second 100,000 cases and just four days for the third 100,000 cases, he said.
The number of cases is believed to represent only a fraction of the true number of infections, with many countries only testing the most severe cases in need of hospitalisation.
"We are not helpless bystanders. We can change the trajectory of this pandemic," Tedros said.
He called for a mixed approach, which he likened to a football match, after he and FIFA chief Gianni Infantino jointly launched a campaign aimed at spreading the message of how to protect against infection "to kick out coronavirus." "You can't win a football game only by defending. You have to attack as well," he said.
"Asking people to stay at home and other physical distancing measures are an important way of slowing down the spread of the virus and buying time, but they are defensive measures that will not help us to win," he warned.
"To win, we need to attack the virus with aggressive and targeted tactics," he said, reiterating a call for "testing every suspected case, isolating and caring for every confirmed case and tracing and quarantining every close contact."
But the WHO chief acknowledged that a number of countries were struggling to take more aggressive measures due to a lack of resources and access to tests.
Tedros praised the great energy being put into research and development to find a vaccine and of drugs to treat COVID-19.
But he said that "there is currently no treatment that has been proven to be effective against COVID-19," and warned against the use of drugs not proven to work against the disease.
"Using untested medicines without the right evidence could raise false hope and even do more harm than good, and cause a shortage of essential medicines that are needed to treat other diseases," he said.
Among other things, countries are looking at using antimalarial drugs as a treatment against the new coronavirus.