CARACAS (Reuters) - Venezuela has arrested Diego Salazar, a relative of former oil czar Rafael Ramirez, as part of an investigation into a money laundering scandal in Andorra, the South American country s state prosecutor said on Friday night. President Nicolas Maduro is overseeing what his administration calls a  crusade  against corruption in the member of the Organization of the Petroleum Exporting Countries (OPEC). Some 65 oil executives have been detained in a deepening purge that could also see the leftist leader consolidate his grip over the energy sector and sideline rivals. The Salazar case appears to relate to what the United States in 2015 said were some $2 billion in laundered funds from Venezuelan state oil company Petr leos de Venezuela, S.A. [PDVSA.UL], known as PDVSA, at the private bank Banca Privada D Andorra (BPA).  Saab did not specify Salazar s role or details on the money laundering, except that it involved around 1.35 billion euros in 2011 and 2012, but he said the case was bound to grow.   I want to highlight that this citizen will likely not be the only one detained and the only one investigated,  Saab said in a phone call to state television announcing the arrest.  The arrest is bound to cast the spotlight on Ramirez, who was the powerful head of PDVSA and the oil ministry for a decade before Maduro demoted him as a envoy to the United Nations in 2014. A protracted rivalry between Maduro and Ramirez has increased in the recent weeks, sources close to the situation said this week, especially after Ramirez wrote online opinion articles criticizing PDVSA s production slump and the government s handling of Venezuela s crisis-hit economy. Maduro sacked Ramirez, who was thought to have presidential ambitions, from his job this week and summoned him back to Caracas from New York, the people with knowledge of the situation said. Ramirez and PDVSA did not respond to a request for comment on Friday. Salazar could not immediately be reached for comment. 