The curfew comes as Moscow has intensified attacks on Ukrainian cities, including the capital, Kyiv.
Kyiv will impose a 35-hour curfew from Tuesday night amid a “difficult and dangerous moment” after several Russian strikes in the capital, according to Mayor Vitali Klitschko.
The curfew from 8pm (18:00 GMT) on Tuesday until 7am (05:00 GMT) on Thursday was a “decision of the military command”, Klitschko, a former boxing champion, said on Tuesday.
The announcement came as Russia launched fresh attacks in Ukraine’s capital, which has nearly been encircled by Russian troops in the third week of the invasion that has caused the biggest refugee crisis since World War II.
Kyiv has been through the worst of the fighting since Russia invaded Ukraine on February 24, but the Russian military is slowly closing in on the city and the shelling has intensified.
Two large blasts echoed across the centre of the city just before dawn on Tuesday, after late on Monday, tracer bullets flashed across the night sky as Ukrainian forces apparently targeted an enemy drone.
“Today is a difficult and dangerous moment,” Klitschko said in a statement on Telegram.
“This is why I ask all Kyivites to get prepared to stay at home for two days, or if the sirens go off, in the shelters,” the mayor said.
“Movement around Kyiv without special permits is forbidden. It is only allowed to go outside with the aim to get to the shelters,” he added.
“The capital is the heart of Ukraine, and it will be defended. Kyiv, which is currently the symbol and forward operating base of Europe’s freedom and security, will not be given up by us.”
Three leaders in Kyiv
A witness told the Reuters news agency he saw a high-rise apartment block in flames after being hit by artillery.
Firefighters tried to douse the blaze and rescue workers helped evacuate residents trapped inside using mobile ladders. A body lay on the ground in a bag.
The curfew comes as the Polish, Czech and Slovenian prime ministers were travelling to Kyiv by train on Tuesday in the first visit by foreign leaders to the capital.
Kyiv imposed a similar curfew on February 26 just after Moscow launched its invasion.
Thousands of people have been killed in the conflict and millions more displaced.
Russia, which denies targeting civilians, calls its actions a “special military operation” to “denazify” the country, a claim that Ukraine and its allies reject as a pretext for an unjustified and illegal attack.