Pope Francis on Wednesday called for an end to violence in Venezuela that has killed at least 13 people and urged politicians to take the lead in calming the nation's worst unrest for a decade.

Both political camps were marching in cities around the country, with the focus being rallies in different parts of the capital Caracas: one by female opposition supporters and another by agricultural workers who support the socialist government.

Students and other opponents of President Nicolas Maduro are demanding he quit over grievances including high inflation, shocking levels of violent crime, shortages of basic foodstuffs, and what they say is his repression of political rivals.

The protests are the biggest challenge to Maduro's 10-month-old administration, although there is no sign they could topple him or affect the OPEC nation's oil shipments.

Pope Francis told tens of thousands of people in St. Peter's Square he was "particularly concerned" about recent events.

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Discussions must tackle 'concrete issues,' said Pope Francis.

"I sincerely hope the violence and hostility ends as soon as possible, and that the Venezuelan people, beginning with the responsible politicians and institutions, act to foster national reconciliation through mutual forgiveness and sincere dialogue," Francis said during his weekly address.

Discussions must be based on "truth and justice," he added, and be able to tackle "concrete issues for the common good."

Maduro, a 51-year-old former bus driver and union boss, has invited church, business and opposition leaders to a "national peace conference" at the presidential palace on Wednesday.

However, opposition figures are not expected to attend.

In the latest of near-daily demonstrations by both sides, female opposition supporters donned white clothes to march in silence from a western Caracas neighbourhood to a nearby National Guard base, carrying photographs of victims of alleged brutality by the security forces.

Meanwhile, pro-Maduro farm workers clad mostly in the bright red of the ruling Socialist Party marched in the centre of the capital under the slogan "Sowing peace and harvesting life!"

​Tense in Tachira

Opposition demonstrations began at the start of the month, but mushroomed after three people were shot dead on Feb. 12.

Maduro, who narrowly won a presidential election last April to replace his mentor, the late leader Hugo Chavez, has accused foreign media of being in league with "imperialists" abroad to project an image of chaos and repression.

About 150 people have been injured during the two-week crisis, and more than 500 people arrested. The government says the vast majority of them have since been freed pending trial.