CARACAS, Venezuela -- Hundreds of thousands of whistle-blowing demonstrators demanding President Hugo Chavez's resignation took to Venezuela's streets Friday, the 19th day of a general strike that has crippled the oil-rich nation's economy.
Some protesters waved Venezuelan flags while others painted their faces in the national colors of red, yellow and blue. Traffic lightened to a minimum on Caracas's normally jammed streets because of the protests -- and because many cars were out of gas with most filling stations closed.
Strike leaders called Friday's demonstrations, converging at the Plaza Venezuela in the heart of the capital, a "mega-march" and a "takeover of Caracas."
Gina Gonzalez, a 21-year-old law student, said she was protesting "because I want Chavez out. He has broken the state of law and doesn't have democratic ideals."
The Chavez government has pledged to heed a Supreme Court ruling this week to return control of the Caracas police from the military to the mayor -- a leading Chavez opponent.
Striking oil executives, on the other hand, have defied the Supreme Court's order on Thursday to immediately return to work. Instead, they staged rallies at assembly halls across the country.
"All Venezuelans must obey the rulings of the Supreme Court," said Vice President Jose Vicente Rangel.
Across town from the anti-Chavez demonstration, about 10,000 Chavez supporters gathered for an impassioned rally.
"We cannot stay at home while the opposition is holding a march to overthrow Chavez," said demonstrator Jesus Navarro.
The State Department issued a travel warning Friday urging U.S. citizens visiting Venezuela to leave and those intending to go to change their plans. The warning cited concerns over deterioration of the political and security situation.
Non-emergency employees of the U.S. Embassy and their families are also being asked to return immediately to the United States.
The situation was volatile. Nineteen people were killed after an anti-Chavez demonstration was fired on by snipers in April, prompting a military coup that ousted Chavez for two days. Sporadic violence since has claimed more lives and wounded dozens.
State television showed gasoline tanker trucks protected by soldiers entering Caracas, but most gas stations remained closed for lack of fuel, and the few still open had lines up to a mile long.
Juan Vaquero, president of the National Federation of Gasoline Retailers, said more than 80 percent of Caracas' gas stations were closed.
The general strike, begun Dec. 2 to force Chavez's resignation or early elections, has reduced the oil output by the world's fifth-largest exporter to less than 10 percent of normal and pumped up global oil prices.
The price of Organization of Petroleum Exporting Countries' seven crude oils hit a two-year high of $29.56 a barrel because of the Venezuelan crisis.
Chavez discussed the situation by telephone with his Iranian counterpart, Mohammad Khatami, whose country is a founding member of OPEC, as is Venezuela, OPEC's official news agency reported.
Executives at Petroleos de Venezuela S.A., the state oil company, ignored the Supreme Court ruling ordering them back to work while the court determines the legality of the oil strike. PDVSA workers say Venezuela's constitution gives them the right to strike.
Juan Fernandez, a PDVSA executive fired by Chavez, said the stoppage will continue despite the Supreme Court order. "Not one step back," he declared at a news conference, using the strike slogan emblazoned on demonstrators' black headbands.
Venezuela's oil production is down to less than 300,000 barrels per day from about 3 million barrels a day in November. About 40 tankers await loading. Only three tankers have left since the strike began, compared with about 12 a day before the strike.
The military appeared set to intervene to bring one gasoline-laden tanker into port.
Army Gen. Alberto Jose Gutierrez said Navy Vice Admiral Miguel Camejo Arena would soon seize the Pilin Leon, which is loaded with 280,000 barrels of gasoline off the western city of Maracaibo.
"If anyone tries to block the transport process, they will be disobeying a Supreme Court ruling, and judicial measures will be taken," said Gutierrez.
Saul Perez, the head of the port of Maracaibo, resigned Friday, saying he refused "to be responsible for the disaster that can occur" with untrained crews handling tankers and tug boats.
The Organization of American States is mediating talks between the government and the opposition, but OAS Secretary General Cesar Gaviria said a breakthrough appeared distant. Opposition negotiators said government officials didn't attend scheduled talks Friday. They vowed to continue daily protests.
General strike organizers say Chavez has wrecked the economy and polarized the nation. Venezuela's economy shrank 6 percent the first nine months of this year, unemployment is 17 percent and inflation is 30 percent.
The constitution says a recall vote may be held halfway into Chavez's term, which would be in August.