The Venezuelan government has fired four oil company executives who are taking part in the general strike against President Hugo Chavez.

Officials dismissed the executives with the state-run PDVSA monopoly Thursday on the eleventh day of the strike aimed at ousting Mr. Chavez.

The continued work stoppage has halted oil exports, although the government said Wednesday it regained control of the vital industry. Officials said several oil tankers were heading for foreign ports, but opposition leaders denied the claims, saying no tankers had left Venezuelan shores.

The chief mediator in talks between the government and opposition is warning violence could break out unless the sides reach an agreement.

The secretary-general of the Organization of American States, Cesar Gaviria, says both parties continue to have differences, but he urged them to continue efforts to resolve the crisis.

Mr. Gaviria said Wednesday he was fearful the longer the crisis continues, the greater the possibility for violence. Negotiations were continuing Thursday.

The general strike has created shortages of food, drinking water and cash.

The government says the work stoppage is costing $50 million per day in Venezuela, the world's fifth-largest oil exporter.