Boris Johnson has been forced to abandon much of his plan for easing lockdown in England, with the prevalence of coronavirus "likely to be rising for the first time since May".
But he suggested its not enough to just act locally.
"It is also my responsibility to look again at the measures we have in place nationally in light of the data we are seeing about incidence," the prime minister said.
"With those numbers creeping up, our assessment is that we should squeeze that brake pedal… in order to keep the virus under control."
As such several planned easings have been scrapped until August 15 "at the earliest":
Casinos, bowling alleys, skating rinks and other close contact services must remain closed
The government had been planning to move to the next phase of lifting lockdown on August 1, by reopening of higher-risk settings.
He said that easing will not go ahead for at least another two weeks.
Indoor performances will not resume
The moment many in the entertainment industry had been waiting for will not come for at least two more weeks.
At the last stage of lifting lockdown, it was announced that outdoor arts performances - including theatres, opera, dance and music - would be allowed to resume from July 11.
Theatres and concert halls were also allowed to open but were told live performances were not permitted, meaning many chose to remain closed.
Many had been bracing to restart performances with social distancing measures in place from this weekend, but must now wait until August 15 at the soonest.
Pilots of larger crowds in sports venues and conference centres will not take place
For the first time since lockdown, some sports venues were preparing to take part in a trial this weekend which would have allowed fans to watch events indoors.
A two-day county cricket friendly between Surrey and Middlesex took place with spectators in attendance earlier this week, but it appears that for the time being that will be as far as it goes in a tightening of restrictions to limit the spread of coronavirus.
The World Snooker Championship started on Friday with fans in attendance, with further spectators due for the rest of the 17-day event.
Some 5,000 racegoers had been due to attend the Glorious Goodwood Festival on Saturday. Organisers said they are "very disappointed" but that "public health is paramount".
With the rule change, spectators will not be allowed into any of these events until August 15 at the earliest.
Wedding receptions of up to 30 people will not be permitted
Boris Johnson apologised to the many people whose wedding plans this weekend will have been disrupted by his announcement.
It effectively ruins any plans for a wedding party this weekend, but ceremonies will be allowed to continue, so long as the venue is following Covid-secure guidelines.
"I know that the steps we are taking will be a real blow to many people, to everyone whose wedding plans have been disrupted," the prime minister said.
"And I’m really, really sorry about that but we cannot simply take the risk."
Face coverings will be mandatory in more indoor settings from August 8
Mr Johnson said it would be made compulsory for people to wear face coverings in places where people are likely to come into contact with others they do not normally meet.
It means from August 8 face coverings must be worn in museums, galleries, cinemas and places of worship.
The prime minister said there would be "greater police presence" to ensure face coverings are worn and said local authorities had been instructed to close down premises and cancel events which are not following Covid-secure guidance.