Three more people were killed in Venezuela in clashes between police and anti-government protesters, raising the death toll from weeks of demonstrations to 24.

Police on Wednesday fired tear gas and water cannon at scores of rock-hurling students in the capital, Caracas, where about 3,000 students marched to mark a month since the first deaths in weeks of demonstrations.

There were similar opposition protests in the cities of San Cristobal, Merida and Valencia.

The demonstrations have been fuelled by public fury over deteriorating living conditions in the oil-rich South American country. Violent crime, shortages of essential goods like toilet paper, and inflation have combined to create the most serious challenge yet for leftist President Nicolas Maduro.

A student and a civilian were killed during protests in Venezuela's third city Valencia, while a member of the Bolivarian National Guard died in clashes in the nearby city of Naguanagua.

The governor of Carabobo state, home to both cities, blamed anti-government "snipers" for the student's death in a friendly fire incident. But local media said Jesus Acosta, 20, died from a shot to the head near his home, adding that he was not participating in protests at the time.

Guillermo Sanchez, 42, died of a bullet wound and was shot outside his home, Valencia's opposition Mayor Miguel Cocchiola said on Twitter.

Ameliach said Captain Ramso Ernesto Bracho Bravo died from a gunshot.

Sniper accusations

Since the protests began, opposition leaders and students, as well as government authorities, have accused each other of backing radical groups that attack demonstrations with firearms.

Maduro met with cabinet members late on Wednesday and agreed to deploy security forces in hot spots and arrest people financing and supplying "these violent groups" of the opposition, Communications Minister Delcy Rodriquez said on Twitter.

The Caracas march had not been approved by authorities, with Maduro saying the demonstrators were simply looking for trouble. The president announced this week he was banning any protests in the centre of the capital as long as the opposition refuses to hold talks with the government.

But the students turned out anyway, chanting slogans and demanding the release of protesters detained in earlier demonstrations.

Hilda Ruiz, a student leader from Central University, told AFP news agency the marchers also wanted authorities to respond to allegations of police torture and to punish those responsible for the deaths of demonstrators.

The anti-government protests first erupted on February 4 in the western city of San Cristobal, reaching Caracas on February 12 when three people were killed after an opposition protest ended in clashes with security forces.

South American foreign ministers met in Santiago, Chile on the Venezuelan crisis and agreed to form a commission to support talks between the government and the opposition.

The goal of the commission of foreign ministers of the regional bloc UNASUR is to "accompany, support and advise on a broad and constructive political dialogue".