Caracas (AFP) - Venezuela's government on Thursday rejected what it called the United States' "interventionist obsession" after US President Barack Obama backed steps for a referendum on removing his Venezuelan counterpart Nicolas Maduro from power.

Obama warned Maduro's government on Wednesday not to block the opposition's "legitimate" efforts to hold a recall referendum.

"The interventionist obsession of the US government is unacceptable," the Venezuelan foreign ministry responded in a statement on Thursday.

Maduro's opponents blame him for an economic crisis that has caused food shortages and prompted deadly looting.

They have launched proceedings to call a referendum this year, but Maduro has mounted legal challenges, vowing it would not take place.

Obama described the situation as "very serious."

Maduro's government retorted: "It is contradictory and illogical to urge the Venezuelan government to disregard the state of law with the sole end of satisfying the antidemocratic interests of the Venezuelan opposition."

The government alleged members of the opposition MUD coalition are working for the United States, which it has long accused of trying to depose Venezuela's socialist leaders.

The two countries have not exchanged ambassadors since 2010, but last week resumed high-level talks aimed at easing the crisis.