Venezuelan President Nicolas Maduro has hit out at the US deployment of three warships off the coast of Venezuela as part of efforts to curb drug trafficking, calling the operation an "illegal" attempt at regime change.

Maduro's response on Friday to the US deployment came after the Trump administration stepped up the pressure on him, doubling its bounty to US$50 million this month on drug charges against the leftist strongman.

Earlier this week, a US source confirmed that three Aegis-class guided missile destroyers were heading to international waters off the South American country. US media reported that 4,000 Marines could also be deployed.

"What they're threatening to do against Venezuela – regime change, a military terrorist attack – is immoral, criminal and illegal," Maduro told lawmakers.

"This is a matter of peace, of international law, for Latin America and the Caribbean.

"Anyone who commits an act of aggression against a country in Latin America is attacking all countries."

In 2020, during Trump's first term in office, Maduro and other high-ranking Venezuelan officials were indicted in US federal court on several charges including participating in a "narco-terrorism" conspiracy.

The US Justice Department accused Maduro of leading a cocaine trafficking gang called "The Cartel of the Suns" that shipped hundreds of tonnes of narcotics into the United States over two decades, earning hundreds of millions of dollars.

Washington does not recognise Maduro's last two election victories.

Maduro said this week that he would be deploying 4.5 million militia members across Venezuela in response to US "threats" and called for weekend rallies decrying Washington. (AFP)