US Secretary of State John Kerry has urged Venezuela's government to hold talks with student protesters, as the death toll from nationwide demonstrations hit 17 and new marches were planned in Caracas.

"They need to reach out and have a dialogue, and bring people together and resolve their problems," Kerry told reporters in Washington on Friday, renewing his criticism of Maduro's government for its heavy-handed response.

They need to sit down and come together and talk about the future of Venezuela. John Kerry, US Secretary of State

"We need a dialogue within Venezuela, not arrests and violence in the streets," said Kerry, adding that the US was working with Colombia and other countries to bolster mediation efforts.

"They need to sit down and come together and talk about the future of Venezuela and how they can best affect that future in a peaceful and responsible way," he said.

Reporting from the industrial city of Valencia, east of Cararcas, Al Jazeera's Chris Arsenault said: "Calls from the US for dialogue probably won't do a lot of good, as the government believes Washington and its Colombian allies are backing the protests."

Uruguay's President Jose Mujica has offered to mediate, if he is invited by both sides, and this seems like someone who has more trust.

Brazil also has the credibility to help bring the parties together, but so far they haven't made a public offer," our correspondent said.

With no sign of a breakthrough after three weeks of escalating street rallies, students and dissidents assembled in the capital on Friday to denounce human rights violations allegedly committed by police.

Meanwhile, the Venezuelan government announced a rise in fatalities linked to the protests and said it was investigating 27 cases of human rights abuses.

Some of the deaths have been attributed to violent clashes with police, but other victims have been shot by unidentified gunmen. The government has denied all links to such killings, reported the AFP news agency.

'Inexcusable' violence

Friday's main protest was organised by the Venezuelan Penal Forum, which said it had identified cases of human rights abuses as of Wednesday. At noon local time, demonstrators began to gather in the neighbourhood of Mercedes, in eastern Caracas.

Maduro, who accuses protesters of plotting a coup with support from the US, met on Wednesday with business and church leaders, intellectuals, journalists and politicians at his presidential palace in what was dubbed a national peace conference.

But the main umbrella opposition group, known as MUD, stayed away. Beyond speeches by the president and other participants, no dialogue took place and no action was taken.

Venezuelan Foreign Minister Elias Jaua, speaking in Brasilia on Friday, said the government had Brazil's support for a meeting of UNASUR, the South American regional group of countries, to discuss the protests, which he dubbed an "attack on democracy in Venezuela".