CARACAS, July 27 (Reuters) - Opposition lawmaker and oncologist Jose Manuel Olivares, who led protests over Venezuela’s crumbling health sector, said he has fled the crisis-stricken country after his family received threats that they would be persecuted unless he quit politics.

Olivares joins the growing ranks of opposition activists who have been forced into exile, arrested, or barred from politics during leftist President Nicolas Maduro’s crackdown on dissent.

In a letter tweeted late on Thursday, Olivares said he was forced to leave Venezuela because his mother, brother and wife, who gave birth to their son a few months ago, had been threatened.

“My brother had already received threats last year, and was even locked up in the (intelligence agency) SEBIN for several months. Now, as of a few weeks ago, my wife, mother, and my brother received threats once again. They were warned that they would be persecuted and accused if I did not step away from politics and protests in the health sector,” Olivares wrote, without describing the nature of the threats.

The lawmaker, who represented the coastal state of Vargas, was at the forefront of protests decrying medicine shortages, crumbling health infrastructure, and a mass emmigration of doctors. He also helped organize research into the state of hospitals after the Health Ministry stopped publishing key data on disease and infant mortality.

“Maduro’s government thinks that with this persecution they hurt me or weaken me, but it is the complete opposite,” Olivares wrote. “They are the ones exposing themselves, because of their evil and cowardice as they persecute my family and newborn son, as well as because of the fear they have of people protesting and demanding their rights.”

Olivares did not immediately respond to requests for information about his whereabouts. Venezuela’s Information Ministry did not respond to a request for comment.

Maduro says the opposition is in fact a coup-plotting, Washington-backed elite that is seeking to topple him under the guise of peaceful protests. His government says the financial downturn is due to an “economic war” waged by his enemies.

Most economists instead blame shortages, hyperinflation, and five straights years of economic contraction on Venezuela’s creaking state-led system. (Reporting by Alexandra Ulmer; editing by Jonathan Oatis)