Demonstrators fill up a bottle with gasoline during protests against Nicolas Maduro's government in San Cristobal, about 410 miles (660 km) southwest of Caracas, Feb 26, 2014. [Photo/Agencies]

Tense in Tachira

About 150 people have been injured during the two-week crisis, and more than 500 people arrested. Fifty-five people remained behind bars on Wednesday, including 11 security officials held for presumed rights abuses, the government said.

Maduro said on Wednesday more than 50 people had died from the unrest. He was referring not only to the 13 people shot or directly killed around protests and rallies, but also those indirectly affected by, for example, being blocked from getting to hospital.

"An 84-year-old lady died in east Caracas yesterday because they had her held up in a street blockade for more than three hours," he said. "She died in her family's car."

The worst of the violence is centered on the western state of Tachira, bordering Colombia, where officials in several municipalities reported the looting of a supermarket, clothes shops, discos and other businesses overnight. Several people were hurt by plastic buckshot fired by security forces.

Ricardo Hernandez, mayor of Cardenas municipality, close to the state capital San Cristobal, blamed the looting on hooded motorcyclists, and said he had needed to call on reinforcements from the national police and National Guard troops.

"Take the necessary precautions, such as having telephones close to hand, doors tightly closed," Hernandez exhorted residents. "Keep bells or whistles nearby in order to alert the neighbors."

Farmers in Jauregui municipality, a major supplier of vegetables to the rest of the country, said they have 15,000 tons of products they have not been able to send to markets because of the insecurity and barricaded highways.

Shortages are particularly acute in many areas of Tachira, where blocked roads and the threat of violence mean delivery trucks have not reached stores for days, residents say. Moderate opposition figures have called for peaceful protests only and voiced despair at the tactics of barricading streets and burning trash in mostly middle-class neighborhoods that are already overwhelmingly pro-opposition.

Venezuelans are approaching a long weekend for Carnival, when families typically head to the beach. Possibly with an eye to taking the heat out of the protests, Maduro extended the break by also declaring Thursday and Friday national holidays.

Farmers march in support of Venezuela's president	Motorcyclist rally supporting Venezuela's President Maduro