Venezuelan President Nicolas Maduro issued the government's 2017 budget by decree, bypassing the opposition-held legislature in a move that could deepen the country's economic crisis.

"Here is the 2017 budget and debt law. May it be fulfilled. I ask for the support of the people, the military and the street," Maduro said at a signing ceremony in Caracas on Friday, attended by hundreds of supporters.

The move came a day after Venezuela's Supreme Court -- which the opposition says is stacked with Maduro supporters -- ruled that the leftist leader did not have to submit his budget to the National Assembly, despite a constitutional requirement to do so.

The court said the ruling aimed to "maintain the functioning of the state, the guarantee of fundamental rights and constitutional order."

The court has said that the National Assembly is in contempt because it has sworn in three opposition legislators whose election is still being challenged amid allegations of fraud.

Maduro said the decree was necessary because "there is no National Assembly," but rather "a political forum operating in contempt of court."

The president and the National Assembly have been locked in battle since the center-right opposition took control of the legislature in January, ending the left's 17-year monopoly on power.

- 'Illegal budget' -

The South American OPEC member's oil-dependent economy has plunged in tandem with global crude prices in the past two years.

The new budget is based on an oil price of $30 a barrel, which Maduro called a conservative estimate.

It allocates 73.6 percent of spending to social programs and comes with a law to limit new government debt.

Jose Guerra, the lawmaker who heads the National Assembly's budget commission, said the legislature would reject the budget.

"We are going to tell the government that this is an illegal budget," he warned.

He said the Assembly would "call on financial institutions to abstain" from lending money to the government, because state debt requires approval from the legislature.

Economists said the new budget would only generate more international mistrust of Venezuela, which is already struggling to get to grips with a crushing economic crisis.

The budget-by-decree is "an attack on constitutional order in a domain that is so important for the functioning of the economy," said the National Academy of Economic Sciences in a statement.

It stands on legally shaky ground, which could scare off foreign banks and contractors, some experts warned.

"This budget has no legal validity, and expenses, commitments and contracts made under it could be disregarded," said constitutional law expert Jose Ignacio Hernandez.

The Supreme Court is taking over an authority "that can only be fulfilled by the people's representatives, in other words the Assembly," Hernandez said.

The latest battle between the executive and the legislature comes as Maduro's opponents seek to call a referendum on removing him from office.

Fed up with shortages of food and basic goods, spiraling inflation and rampant crime, seven in 10 Venezuelans want a change in government, according to a recent opinion poll.