Caracas: An opposition candidate in Venezuela’s upcoming legislative elections was shot dead during an event Wednesday, alongside the wife of a jailed opposition leader, an official said.

The December 6 elections are critical to President Nicolas Maduro’s socialists remaining in power.

“Luis Manuel Diaz, local leader of the Democratic Action party in Altagracia de Orituco (Guarico state) has just been shot dead,” the party’s chairman Henry Ramos Allup said on Twitter.

Ramos Allup said Diaz was standing next to Lilian Tintori, wife of jailed opposition leader Leopoldo Lopez, who is in prison for incitement to violence in 2014 antigovernment protests.

He added that the shooter, whom he believed to be a member of an “armed gang” linked to the ruling United Socialist Party of Venezuela (PSUV), carried out the attack from a vehicle.

In a statement, the Union of South American Nations (UNASUR) expressed regret over the death and rejected “all forms of violence that could affect the normal development of the electoral process.”

UNASUR is a 12-country regional organisation and the only international group accredited by socialist President Nicolas Maduro’s government to monitor the upcoming elections.

Opinion polls indicate the opposition is poised to win control of the National Assembly for the first time since Maduro’s mentor, late leftist firebrand Hugo Chavez, came to power in 1999.

But opposition leaders accuse the PSUV of seeking to steal the vote.