International concerns are mounting over the economic and political crisis in Venezuela, where the military on Saturday was holding a second day of exercises ordered by embattled President Nicolas Maduro.

With the oil-dependent country's economy imploding under recession and hyperinflation, public sentiment is backing Maduro's ouster.

But the socialist president is digging in.

He imposed a state of emergency this week and ordered the two-day war games to show that the military can tackle domestic and foreign threats he says are being fomented with US help.

After deploying its Russian-made strike aircraft across Venezuela's skies on Friday, the military ran other units through their paces on Saturday, state television showed.

Several anti-riot squads were shown. And missiles, including a Russian BUK anti-aircraft missile on a mobile launcher, were presented, but not fired.

The defense minister, General Vladimir Padrino Lopez, said civilian militias were integrated into the defense strategy of the armed forces "under the constitutional principle of shared responsibility between the state and society."

The opposition, which has a majority in the National Assembly, this week rejected the state of emergency.

It led protests on Wednesday demanding a recall referendum against Maduro on the basis of a petition that garnered 1.8 million signatures. Seventy percent of Venezuelans want a change of government, polls say.

But the Supreme Court, stacked with judges loyal to Maduro, overruled the legislature and said that the emergency decree was "constitutional."

Separately, electoral officials have been dragging their feet in validating the petition.

- 'Coup' risk? -

Opposition leader Henrique Capriles, whom Maduro narrowly beat to the presidency in 2013 elections following the death of Hugo Chavez, has given dire warnings about the mounting public frustration.

The risk is that "along the way there is a social explosion and, as we have repeated, a coup d'etat," Capriles said in an interview with the Spanish newspaper El Pais.

"We don't want a coup d'etat. The solution for Venezuela isn't a military uprising. That would be worse than what we have today."

There has so far been no sign of faltering loyalty in the armed forces, with top brass rallying to the government, a third of whose ministries are run by active or retired senior military men.

But low-ranking soldiers have seen their pay cut to a poverty-level pittance under Venezuela's inflation rate, which at 180 percent last year was the world's highest.

- Mediation bid -

The United States has been generally careful not to play into the accusations Maduro regularly makes against it.

The State Department has thrown its support behind a South American-sponsored mediation effort started this week and headed by former Spanish prime minister Jose Luis Rodriguez Zapatero.

"We support this dialogue as a way of guaranteeing respect for the will of the Venezuelan people, the rule of law, the separation of powers, and the democratic process," a State Department spokesman, Mark Toner, said in a statement on Friday.

Chile, Argentina and Uruguay also jointly appealed for "effective political dialogue" to take hold.

But Zapatero has warned that launching serious talks between the entrenched Venezuelan government and the opposition would be "hard," with no guarantee of success.

Maduro has already said he hopes the outcome of any talks would be convince the opposition to drop its "coup mindset."

And the opposition coalition in turn has said the priority of dialogue must be to make sure that the recall vote is held.