By Alexandra Ulmer and Deisy Buitrago

CARACAS (Reuters) - Venezuela's opposition-led National Assembly in a rowdy session on Sunday pressed to put Nicolas Maduro on trial for violating democracy, days after authorities nixed a recall referendum against the unpopular leftist president.

The measure is unlikely to get traction as the government and the Supreme Court have systematically undermined the legislature on grounds it is illegitimate until it removes three lawmakers accused of vote-buying. But it marked a further escalation of political tensions in the crisis-hit OPEC nation.

"It is a political and legal trial against President Nicolas Maduro to see what responsibility he has in the constitutional rupture that has broken democracy, human rights, and the future of the country," said opposition majority leader Julio Borges during a special congressional meeting.

The session was briefly interrupted when around 100 apparently pro-government protesters stormed in, brandishing Socialist Party signs and shouting "The Assembly will fall!" before officials herded them out.

Opposition lawmakers said there were injuries and tweeted photos of two men receiving care after alleged blows to the head. There were also reports some journalists had been robbed of their camera and flak jackets.

"The Socialist Party is showing what it has left. There are no ideas or arguments, only violence!" said opposition leader and two-time presidential candidate Henrique Capriles.

The opposition coalition, seeking to end 17 years of socialism in the South American nation, says Thursday's suspension of its drive for a plebiscite against Maduro shows Venezuela has abandoned democracy.

Ruling party officials accuse the opposition of fraud in their signature drive and say the coalition is seeking a coup to gain control of Venezuela's vast crude reserves, the world's largest.

Despite that oil wealth, Venezuela has plunged into an unprecedented economic crisis, with many people skipping meals due to shortages and soaring prices.

Many Venezuelans fear preventing the referendum increases chances of social unrest in the already volatile and violent country.

The opposition coalition has called for a major peaceful protest on Wednesday, dubbed "The takeover of Venezuela".

'PEOPLE ARE HUNGRY!'

In Sunday's raucous session, lawmakers also traded barbs, with ruling party politicians showing photos of late leader Hugo Chavez while opposition congressmen chanted "The people are hungry and want a recall!"

Likening Maduro to former Chilean dictator Augusto Pinochet and Peru's authoritarian ex-president Alberto Fujimori, opposition lawmakers also vowed to replace deans at the electoral council and judges on the Supreme Court, though that too is unlikely to see the light of day.

Congress concluded the session by declaring that Maduro's government had staged a coup by axing the referendum. And lawmakers unearthed an old accusation, that Maduro was actually Colombian and so is ineligible to be president, though they had yet to offer any proof.

"Stop being ridiculous," said ruling party lawmaker Hector Rodriguez, slamming the session as a "bad circus".

"What you want to do is stage a coup, like in Paraguay, like in Honduras, and like in Brazil. We're not Honduras, nor Paraguay, nor Brazil."

It was not immediately clear how Congress, which will hold another special session on Tuesday, might seek to put Maduro on trial.

The opposition had indeed largely rejoiced when the senate of neighboring Brazil ousted leftist leader Dilma Rousseff last month. Recent shifts to the right in Argentina and Peru have also given the opposition hope of piling regional pressure on Maduro.

Maduro, a former bus driver and union leader, is currently on a four-day foreign trip to seek consensus on supporting oil prices. He has seen his popularity tumble as the recession worsens three years on from the death of his mentor Chavez.

Even former 'Chavista' strongholds in the slums have turned against Maduro, and the opposition frequently claims discontent runs deep among some in the top brass.

"None of you brought even a single photo of Maduro!" opposition lawmaker Luis Emilio Rondon taunted, as his peers chanted "You don't love Maduro!"

(Additional reporting by Marco Bello and Liamar Ramos; Writing by Alexandra Ulmer; Editing by Sandra Maler and Mary Milliken)