Protesters rallied in Chilean capital Santiago and other cities on Thursday afternoon as President Sebastian Pinera sent the first of a promised raft of legislation to Congress in a bid to address calls for an end to Chile's entrenched inequality.

Tens of thousands of protesters gathered for mainly peaceful demonstrations which on Thursday included dancing, some displays of nudism, carnival-type costumes, and effigies of Pinera. There were also more instances of looting at supermarkets and clashes with police.

Prosecutors said on Thursday that since Wednesday night 734 more people had been charged in connection with protests, looting and arson nationwide, with 324 taken into custody in Santiago. More than 7,000 have been charged since Saturday.

Protests that started over a hike to public transport fares boiled over on Friday into riots that have left at least 18 people dead, hundreds injured and millions of dollars' worth of damage to businesses and infrastructure.

Pinera, a billionaire businessman, spoke to the nation on Thursday morning in a televised broadcast, saying he had heard the "loud and clear" demands of Chileans.

The president said he would send a bill to Congress later on Thursday that would overturn a recent hike in electricity rates, one of several measures he said he hopes will turn the violent demonstrations into an "opportunity" for Chile.

He said he would follow it on Friday with a bill to increase the minimum pension by 20 percent.

Ivan Flores, president of the opposition-led chamber of representatives, said lawmakers would skip a previously-planned recess to fast-track the reforms.

UN human rights chief Michelle Bachelet, a former president of Chile, wrote on Twitter on Thursday that she would send a mission to her home country to investigate allegations of human rights violations.

The Chilean government said it would welcome a UN delegation, along with representatives of global NGO Human Rights Watch.

Foreign Minister Teodoro Ribera said on Thursday that there was "no chance" the government would call off the November 16-17 APEC summit and the United Nations climate change conference COP25 in December in Santiago.

"I'm certain that under no circumstances will this come to impact the conferences," Ribera said.

Ribera said Chile's foreign ministry had contacted each of the 20 participants in the Asia-Pacific gathering of nations. "They have expressed no doubt with respect to their attendance."

In Cerrillos, at a former airforce base just southwest of central Santiago, workers continued to lay cement and pound nails at the conference site of COP 25, unaffected by the nearby rioting.

"I'd say 99 percent of construction workers have shown up to work," said Daniel Cruz, a Peruvian worker. But snarled public transportation had forced some to finish early, slowing progress six weeks before the December 3-13 conference. "We're working against the clock."