By Will Grant
BBC News, Caracas
Many businesses in Caracas have been ordered to reduce electricity use
Venezuela has confirmed that eight Colombian citizens have been arrested on suspicion of spying, accused of trying to destabilise its power grid.
Venezuela is currently experiencing its worst electricity crisis for 50 years.
President Hugo Chavez says the problem is partly down to sabotage by government opponents.
Venezuela's relations with Colombia were suspended last year following a dispute over US access to Colombian military bases.
The eight Colombians, arrested last week, are all believed to be members of the same family who have lived in the Venezuelan state of Barinas for more than 15 years.
The Venezuelan interior minister accused the group of taking photos of restricted areas such as electricity substations with the intention, he said, of sabotaging the country's ailing electrical grid.
Asked who the eight were working for, the interior minister would only say that "their nationality is a worrying element".
Relatives of the eight deny the charges, saying the photos were taken by an amateur photographer among them.
The Colombian embassy in Caracas said it was offering legal support to the group but would wait for further evidence to emerge before commenting.
Such is the deterioration of electricity provision in Venezuela, Mr Chavez recently urged what he called a joint "civil, military and police intelligence effort" to track down alleged cases of sabotage to the grid.
The opposition blame the crisis on a lack of investment by his government.
Diplomatic relations between Venezuela and Colombia have been suspended since the US was granted permission to use seven military bases on Colombian soil in 2009.
Ironically, as the interior minister was announcing the arrests, the country's Foreign Minister, Nicolas Maduro, was speaking of his willingness to normalise relations with an incoming administration in Colombia following presidential elections next month.
But analysts say that if such arrests and allegations of espionage continue, that seems an unlikely prospect.