Washington and Moscow have locked horns over the political crisis in the South American country, after Russian planes landed at an airport outside Caracas at the weekend reportedly containing around 100 soldiers and 35 tons of military equipment.

Russian Foreign Minister Sergei Lavrov accused Washington of attempts to "organise a coup d'etat" in the oil-producing nation while US Secretary of State Mike Pompeo warned that the US would not "stand idly by as Russia exacerbates tensions."

Russian foreign ministry spokeswoman Maria Zakharova accused Washington of "aggressive rhetoric" over the issue in a statement on Tuesday.

Moscow is "developing cooperation with Venezuela in strict accordance with the constitution of that country and with full respect for its legal norms," she said.

She added that "the presence of Russian specialists on Venezuelan territory is regulated by an agreement between the Russian and Venezuelan governments on military and technical cooperation that was signed in May 2001".

Venezuela is rich in oil but has plunged into economic crisis, suffering hyperinflation and shortages of food and basic goods.

Washington and its allies support Venezuelan opposition leader Juan Guaido and recognise his claim to be acting president in defiance of Maduro.

Socialist leader Maduro retains the support of Russia and China, US rivals who have offered him political and economic support.

Moscow will continue to "develop constructive, mutually beneficial cooperation" with Venezuela, Zakharova said.