Venezuela's military said on Tuesday that it was on alert at its frontiers following threats by US President Donald Trump and suspended air and sea links with the island of Curacao ahead of a planned aid shipment.

Opposition leader Juan Guaido, who declared himself "interim president" on Jan 23, has vowed to bring aid in from various points on Saturday "one way or another" despite military efforts to block it.

He was recognized by the United States and Venezuelan President Nicolas Maduro has accused Washington of orchestrating a coup d'etat in order to install a puppet regime in Venezuela.

Commanders doubled down on their allegiance to Maduro's government after Trump urged them to abandon the leader.

"The armed forces will remain deployed and on alert along the borders... to avoid any violations of territorial integrity," said Defense Minister Vladimir Padrino.

Venezuela's military is aware that the true goal of the US is to gain control over the South American country's vast oil reserves and gold deposits, Padrino said.

Regional commander Vladimir Quintero later confirmed media reports that Venezuela had ordered the suspension of air and sea links with Curacao and the nearby Netherlands Antilles islands of Aruba and Bonaire.

Shipments of food and medicine for Venezuelans suffering in the country's economic crisis have become a focus of the power struggle between Maduro and Guaido.

Aid is being stored in Colombia near the Venezuelan border and Guaido aims also to bring in consignments via Brazil and Curacao, which is off the coast of Venezuela.

Maduro says the aid plan is a smoke screen for a US invasion. He blames US sanctions and "economic war" for Venezuela's crisis.

Guaido, 35, has appealed to military leaders to switch allegiance to him and let the aid through.

But the military high command has so far maintained its public backing for Maduro－seen as key to keeping him in power.

"We reiterate unrestrictedly our obedience, subordination and loyalty" to Maduro, Padrino said.

Trump has refused to rule out US military action in Venezuela. He raised the pressure on Monday, issuing a warning to the Venezuelan military.

He told them that if they continue to support Maduro: "You will find no safe harbor, no easy exit and no way out. You will lose everything."

Padrino rejected Trump's threat, branding the US president "arrogant".

If foreign powers try to help install a new government by force, they will have to do so "over our dead bodies", Padrino said.

Meanwhile, the US State Department confirmed on Tuesday that US Special Representative for Venezuela Elliott Abrams had met with Venezuela officials recently to ensure the security of US personnel in the South American country.

AFP, Xinhua and AP contributed to this story.