By Andrew Cawthorne and Brian Ellsworth
CARACAS (Reuters) - Mexico's envoy to Caracas was seized overnight then freed on Monday in the latest high-profile kidnapping in Venezuela, where violent crime is routinely listed as citizens' No. 1 worry.
In the classic style of "express" kidnappings that are rife in Venezuela, four armed men seized ambassador Carlos Pujalte and his wife in their car after a reception in the upscale Country Club zone of Caracas around midnight (0430 GMT), diplomats and officials said.
The kidnappers released the couple in a slum before dawn.
"We're so happy he is safe, I've been up following the case all night," said a senior European diplomat, whose own security has been increased in recent months.
Kidnappings, armed robberies and murders are common in the South American OPEC member nation that has enormous oil wealth alongside widespread poverty.
Venezuela's Attorney-General's office said a full investigation was underway.
Mexican Embassy spokesman Fernando Godinez said his boss was recovering fine after his release.
"His health is ok. He and his wife are giving statements (to the police) right now," Godinez told a local radio station. "We regret this situation deeply."
Senior diplomats from Chile and Belarus were also seized in similar incidents last year, according to diplomatic sources.
The Chilean consul, Juan Carlos Fernandez, was injured by a bullet, and beaten during his November kidnapping.
Robbery was the assumed motive of those incidents.
"We don't know yet what happened last night, if they robbed the Mexican ambassador or asked for a ransom or what," said a foreign security expert at one of the embassies in Caracas, who was tracking the case closely. "It's a worrying trend though."
Late last year, Major League Baseball player Wilson Ramos, a catcher for the Washington Nationals, also was kidnapped for two days during a visit home, before being released during a raid by security forces on a mountain hideout.
Crime is arguably the top issue for voters in the run-up to an October presidential election.
Police are often involved, and murder rates make Caracas one of the most dangerous cities in the world, ranking with some war-zones.
Though rich and poor alike complain constantly about crime in Venezuela, the issue has traditionally not weighed heavily on President Hugo Chavez's approval ratings.
The latest poll released on Monday by the local Hinterlaces company gave him a 64-percent approval rating, with 50 percent of those surveyed saying they would vote for him in October.
"Chavez supporters have a strong emotional attachment to him and this has led some of them to fail to assess the situation objectively despite the statistics and the growing evidence of the government's responsibility (for the crime problem)," said Venezuelan analyst Diego Moya-Ocampos of the IHS Global Insight thinktank.
Interior Minister Tareck El Aissami says Venezuela's official annual murder rate is around 48 per 100,000 residents, but non-governmental organizations put the figure higher.
The Venezuelan Violence Observatory, for example, said murders had doubled in the last decade to reach a record of more than 19,000 - or about 60 per 100,000 people - in 2011.
"But in Venezuela we have not had a war. How can this be explained?" the NGO asked in its latest publication, saying political polarization underpinned the problem.
(Additional reporting by Mario Naranjo; Editing by Paul Simao)