Spanish police have arrested a son of one of Venezuela's wealthiest businessmen on suspicion of involvement in money laundering, sources close to the investigation told EFE on Wednesday.

A large police operation aimed at tackling money laundering nabbed a son of Roberto Enrique Rincón, a United States-based business magnate, the sources said, adding that more arrests were expected.

Two courts in Madrid were investigating, in coordination with authorities in Portugal and Andorra, several cases linked to the laundering of money originating in Venezuela, the sources said.

The operation, which is ongoing, was initiated in mid-2017 by National Court Judge Carmen Lamela, and is currently probing seven suspects, the sources said.

The investigation was triggered by a whistleblower who lodged a complaint against managers responsible for Venezuela's state oil company, Petróleos de Venezuela (PDVSA) when the late Hugo Chávez was president.

Lamela had passed the case on to two Madrid courts who have continued to investigate the alleged siphoning-off of some 6 billion euros ($7.1 billion) by senior officials in Venezuela's Energy Ministry, of which several million are suspected to have been diverted through Spain, the sources said.

Rincón has been under investigation for links to bribery payments made to PDVSA, the sources said.