Zimbabwe police manned checkpoints on many main roads on Saturday, searching vehicles for protesters involved in recent anti-government demonstrations.
The crackdown by security forces has been fiercely criticised by the UN human rights office, with allegations of shootings, beatings and abductions of opposition figures, activists and ordinary residents.
Police road blocks were a notorious feature of daily life under former president Robert Mugabe.
But they largely disappeared after he was ousted by the military in November 2017 and his former deputy Emmerson Mnangagwa took power.
"We want to tell members of the public that... we have already set up security checkpoints where police officers and other security institutions will be checking," police spokeswoman Charity Charamba told Saturday's state-owned Herald newspaper.
The aim, she added, is to catch suspected looters and recover property stolen during protests that erupted after Mnangagwa last weekend announced a 150-percent increase in petrol prices.
The Herald said 700 people had been arrested since the violent protests, which it blamed on the opposition MDC party and trade unions.
Police were in action at checkpoints on Saturday in the capital Harare and the second city Bulawayo, AFP reporters witnessed.
In Bulawayo, police officers armed with assault rifles manned roadblocks on every major road, conducting "stop and search" operations.
In both cities, customers seeking to stock up on basic goods tentatively returned to shops that opened for the first time since the protests started on Monday.
'SOCIAL MEDIA BLOCKED'
Long queues formed to buy bread and petrol, which are both in short supply due to Zimbabwe's long-running economic crisis.
"Nothing has changed after the fuel price increase," said one motorist in a queue who identified himself only as Sonny.
In Bulawayo, soldiers escorted fuel tanks delivering supplies to petrol stations.
Social media has been blocked by the government in an apparent attempt to suppress information about the security operation and alleged abuses.
A complete internet shutdown was lifted on Friday.
"The internet was the tool used to coordinate the violence," presidential spokesman George Charamba told state TV.
"There is no way you expect us to sacrifice a national good for the sake of internet. If they want uninterrupted internet, let them abide by the law."
The Zimbabwe Human Rights NGO Forum said it had recorded at least 12 deaths, 78 gunshot injuries and more than 240 incidents of assault and torture.
The United Nations human rights office on Friday urged Harare to "stop the crackdown", voicing alarm over the security forces' "excessive use of force" which included reports of them using live ammunition.
And it called on Zimbabwe's government "to find ways of engaging with the population about their legitimate grievances".
The army and police held a joint press conference late Saturday to deny any misconduct, saying some assailants were wearing official uniforms to pose as security personnel.
"We want to warn those bent on causing mayhem that the law will be applied without fear or favour," defence forces spokesman Overson Mugwisi said.
Mnangagwa, 76, is trying to drum up investment on an overseas tour that started in Russia on Monday and will end with him mixing with world leaders at the Davos summit in Switzerland next week.
Mugabe, now 94, ruled Zimbabwe with an iron fist for 37 years from independence from Britain until he was ousted in November 2017.
The military, fearing that Mugabe's wife Grace was being lined up to succeed him, seized control and forced him to resign before ushering Mnangagwa to power.