Venezuela's President Nicolas Maduro Photo: Spencer Platt / AFP
The Spanish foreign ministry had summoned Venezuela's ambassador in Madrid on Monday to complain after Maduro's comments in a televised address at the weekend.
It was the latest in a series of rows between the countries' leaders after Spain's former King Juan Carlos snapped at the late Venezuelan leader Hugo Chavez "Why don't you shut up?" at a summit in 2007.
Spain's Foreign Minister Jose Manuel Garcia-Margallo said Tuesday he ordered his ministry to summon the ambassador "over some completely insulting and unacceptable comments by President Maduro about Prime Minister Rajoy."
Maduro, Chavez's successor as president, said in a televised address Sunday that Rajoy was a "hitman of the people" for introducing tough new penalties for public order offences in Spain.
Garcia-Margallo retorted on Tuesday that Venezuela itself "has a long way to go in terms of human rights, as numerous statements by the United Nations have made public."
It was the second time in three months that Spain had summoned the Venezuelan ambassador. In April it did the same after Maduro called Rajoy "racist".
When a group of senators from Spain visited Venezuela last week to try to mediate in a political dispute in the former Spanish colony, Maduro called the gesture "vomit-inducing".
The Spanish foreign ministry in a statement on Monday called for "constructive relations" between Madrid and Caracas, "based on dialogue and mutual respect".