Venezuelan President Nicolas Maduro has urged his troops to be "ready" for potential US military action, as a limited number of opposition supporters marched on military barracks in a bid to win the armed forces' support.

The small turnout for yesterday's marches - with participants in the hundreds, not the thousands - is another setback for opposition leader Juan Guaido, following a failed military uprising earlier in the week.

Mr Maduro yesterday instructed the military "to be ready to defend the homeland with weapons in your hands if one day the US empire dares to touch this territory, this sacred earth."

Underscoring the continued military support for his socialist regime, Mr Maduro delivered his televised address from a base in northwestern Cojedes state - where he appeared alongside his defence minister, Vladimir Padrino, and in the presence of more than 5,000 troops.

The United States has refused to take the threat of military action off the table in its push to oust Mr Maduro - although it so far has limited its campaign to ramping up sanctions.

Meanwhile, Russian Foreign Minister Sergei Lavrov has urged US officials "to abandon their irresponsible plans" on Venezuela, calling on all Americans "to act exclusively within the boundaries of international law".

The comment came during a meeting in Moscow between Mr Lavrov and his Venezuelan counterpart, Jorge Arreaza.

The opposition's cause gained renewed support on Saturday from US Secretary of State Mike Pompeo, who issued a video address to the Venezuelan people, telling them: "The time for transition is now."

"You can hold your institutions, your military and their leaders to the highest standards and demand a return to democracy," Mr Pompeo said in the message. "The United States stands firmly with you in your quest."

National Assembly head Mr Guaido, 35, has branded Mr Maduro a usurper over his controversial re-election last year, and in January declared himself acting president, plunging Venezuela into a political crisis that deepened its already grave economic woes.

But Mr Maduro has held firm, bolstered by the continued support of the powerful armed forces.