Interim president Nicolas Maduro, heir to the late Hugo Chavez, has attacked supporters of his rival in the April 14 presidential election as being the "heirs of Hitler."

The opposition, Maduro said on Saturday, are the "heirs of Hitler" because they are conducting a campaign of "intolerance" by criticising the presence of Cuban doctors in Venezuela and local artists that have joined the Maduro campaign.

The leftist Chavez died on March 5 and his vice-president, Maduro, must now run for office in a special election to complete the late leader's term.

His rival is Henrique Capriles, candidate of the unified opposition and the man the cancer-ridden Chavez defeated in an October vote.

Capriles ran a positive campaign against Chavez in October, even as the leftist president slammed him as a pampered member of the "rancid oligarchy" taking orders from Washington.

But with Chavez gone, Capriles, who is Catholic but has Jewish roots, is tearing into Maduro, who he derides as a cheap Chavez clone and a puppet of Havana.

A mid-March poll of 1,100 people by the firm Hinterlaces shows Maduro with 53 percent support against 35 percent for Capriles.