Protests over the past two days had been peaceful, but by Thursday night there were clashes with police throughout the night, as protesters set up barricades of rocks and burning tyres.
At least 80 people were arrested in Togo's seaside capital, Lome, after two days of anti-government protests, as several areas remained blocked off on Friday after security forces clashed with opposition supporters.
"A certain number of protesters were detained over the course of last night, about 80," Civil Service Minister Gilbert Bawara told AFP by telephone.
"They committed or were preparing to commit violent acts, vandalise shops," he added.
Eric Dupuy, the spokesman for Togo's main opposition party, the National Alliance for Change (ANC), said "at least 100 people are still in custody."
Protesters took to the streets in huge numbers on Wednesday and Thursday calling for political reform, in the biggest protest against President Faure Gnassingbe in years.
Gnassingbe came to power in 2005 after the death of his father, Gnassingbe Eyadema, who ruled Togo for nearly 40 years.
The opposition wants to limit a president to a maximum of two, five-year terms and the introduction of two-round voting.
Shops were shut on main roads and in working-class districts of Lome and there was a heavy police presence in the coastal city, AFP journalists said.
In the Be area, where there were clashes with police throughout the night, barricades of rocks and burning tyres were visible.
"We want him to leave. We'll stay here until he goes. We're tired," said one of them, referring to the president.
Residents in some parts of the city said they were afraid to leave their homes. One man in his 40s refused to be filmed or give his name, fearing reprisals from the authorities.
Columns of smoke from tear gas fired by the security forces could be seen in the sky in several areas.
Telephone networks remained sporadic on Friday, with the internet still cut off in some parts of the country.
The heads of a dozen opposition parties met outside the home of the leader of the Panafrican National Party, Tikpi Atchadam, and accused the government of intimidating him.
Atchadam has been credited with bringing together opposition parties and has campaigned alongside the ANC's veteran leader Jean-Pierre Fabre.
Amnesty International in a statement condemned the government response as "a clear violation of the freedom of peaceful assembly."
Shutting down internet services "shows how far the authorities are willing to go to muzzle anti-government criticism", said West Africa researcher Francois Patuel.
Protests have been held elsewhere in the tiny West African nation, including in the north, which has traditionally supported the regime.
In Bafilo, where protesters blocked the main road to Lome to the south and north to the border with Burkina Faso, police fired tear gas, according to Amnesty's Togo director Aime Adi.
Togo's government made an apparent concession to the opposition earlier this week, agreeing to put forward a bill to parliament on constitutional reform.
Lawmakers, who were due to return from their summer break only in October, have been recalled for an extraordinary session on September 12 to examine the proposals.
Civil Service Minister Bawara told AFP next week's session had been planned for a while but said it was not guaranteed that the bill would come up for discussion.
"We hope the text will very quickly be the subject of debate in the national assembly," he said.
"The government can only encourage the majority parties and the opposition to find a compromise to vote on the bill," he added.
Bawara made no direct comment on the calls for Gnassingbe to quit, saying only: "The president was elected democratically.
"The majority of parliament equally has a democratic legitimacy and the opposition should respect these values."
Exact details of the proposals are vague but the government has indicated the mandate provision would not be applied retroactively.
That raises the prospect of Gnassingbe, whose rise to power was met with violent protests 12 years ago, staying in office until at least the next presidential elections in 2020.
He won polls held in 2005, 2010 and 2015 but the opposition disputed the results.
Mohamed Ibn Chambas, the UN's special representative in West Africa and the Sahel, met Gnassingbe and Fabre in Lome on Thursday.
Chambas told state television he had congratulated Gnassingbe on proposing the bill to parliament and encouraged Fabre to join talks with the government to "advance the reform agenda."
Fabre however has told his thousands of followers it was "too late" while Atchadam said he "no longer believed in dialogue" with the regime.