Venezuelan President Nicolas Maduro oversaw a display of the army's Russian hardware on Sunday, with anti-aircraft flak and tank rounds pounding a hillside to show military force and loyalty.

Maduro, 56, is confronting an unprecedented challenge to his authority after opposition leader Juan Guaido declared himself "interim president." 

Guaido has the support of the U.S., Canada and some Latin American countries like Argentina and Chile.

On Sunday, Israel joined the countries backing the 35-year-old opposition leader, and the U.S. administration said it had accepted Venezuelan opposition figure Carlos Alfredo Vecchio as the country's diplomatic representative in the United States.

Australia on Monday joined other Western nations in backing Venezuela's opposition leader Guaido as the country's interim president until fresh elections are held.

In an interview with Turkish broadcaster CNN Turk aired on Sunday and dubbed into Turkish from Spanish, Maduro said Guaido had violated the constitution by declaring himself as the leader of Venezuela.

He also rejected an ultimatum set by some European countries for fresh election in Venezuela, calling those countries "insolent."

Early on Sunday, alongside Defense Minister Vladimir Padrino, Maduro watched a platoon of soldiers release volleys of rocket-propelled grenades, machine-gun anti-aircraft fire and tank rounds at hillside targets, the Russian ordnance kicking up clouds of dust at the Fort of Paramacay, an armored vehicle base.

Maduro said the display showed the world he had the backing of the military, and that Venezuela's armed forces were ready to defend the country.

"Nobody should even think of stepping on this sacred soil. Venezuela wants peace ... and to guarantee peace, we have to be prepared," Maduro said.

Maduro says Guaido is taking part in a coup directed by Trump's hardline policy advisers, who include Cold War veterans John Bolton and Elliott Abrams.

From February 10 to 15, the military is planning larger exercises that Maduro described as the "most important in the history of Venezuela."

The Venezuelan president also denounced an alleged conspiracy aimed at spreading rebellion in the army, saying thousands of messages were being sent to soldiers every day over WhatsApp and other social media platforms from neighboring Colombia.