CARACAS -- Venezuela's embattled President Hugo Chavez Tuesday issued a dire warning to his foes as they staged a "fiscal disobedience" march symbolizing a decision to withhold taxes in support of a 36-day-old strike.

"We will not tolerate this. We will take every measure that has to be taken so that taxes are paid," Chavez said in a nationally broadcast address.

He warned he could implement emergency measures to prevent what he called a sabotage of the economy by strikers who have crippled the vital oil industry.

He did not rule out decreeing a "state of exception" that would allow him to suspend some constitutional guarantees. "All scenarios are possible ... I am preparing for the worse," he said.

As Chavez spoke at a school in west Caracas, thousands of protesters, waving Venezuelan flags and wearing headbands telling Chavez to "go away now," marched in the east of the capital.

The march concluded at the tax collector's offices, where the protesters chanted their determination not to pay a cent in value-added, income or other taxes.

"These taxes have not diminished hunger, they have not provided health and education," legal assistant Sergio Contreras, 22, said as he handed out tax forms for people to tear up in protest.

"The president must realize people are tired of his populism, of the hunger and the violence," he said.

Opposition leaders have said they were considering extending the civil disobedience campaign to non-payment of public services.

Supporters of the embattled leftist-populist president have held their own demonstrations in recent days to demand justice for the deaths of two pro-Chavez militants shot dead during clashes on Friday.

The deaths further fueled tension as negotiations between the two sides failed to produce significant results and the opposition pledged to pursue its strike, which further divided the polarized south American country.

Chavez has repeatedly made it clear he would not cave in to the pressure, and he has claimed major successes in his military-backed efforts to bring oil output and exports back to normal.

Energy Minister Rafael Ramirez said that the Petroleos de Venezuela (PDVSA) state oil firm may be split into two regional branches as part of a plan to restore production to pre-strike levels.

Ramirez told the ***New York Times*** the plan also entailed slashing the company's "exorbitant bureaucratic costs," which he estimated at one billion dollars, and getting rid of many executives who have joined the strike.

While the strike has mainly targeted PDVSA, a few other sectors have also been affected, causing shortages in some basic items.

In east Caracas, where the opposition has strong support, shopping malls, cinemas and fast-food franchises remained closed, but a number of business owners who had participated in the strike have reopened their doors in recent days.

Several schools that were closed for the Christmas holidays reopened Tuesday, but others remained shut.

Banks continued to operate on a restricted timetable despite a government order to resume regular working hours, and bank employees' unions were considering launching a 48-hour strike in coming days.

The opposition, headed by the largest employers and labor federation, also engaged in preparations for a planned February 2 referendum on the president's mandate.

Chavez, whose term ends in 2006, has called the referendum unconstitutional and has insisted he would not recognize its outcome.